US2291788A - Combined gate and riser - Google Patents

Description

9 M. BEAN 2,291,783

COMBINED GATE Am) RISER Filed Aug. 1, 1940 4 Sheets-Sheet 2 INVENTOR Name/.5 BfA/V Aug. 4, 194 2. 'M. BEAN COMBINED GATE AND RISER iled Aug. '1 1940 4 sheets-she t :s

INVENTOR Mame/5 65AM. A 5 rzanf ATTORN Y Patented Aug. 194 2 comimrn ears sun-mean Morris Bean, Ieilow Sprints. Ohio V Application August 1, 1940, Serial No. 349,033

This invention relates to the art of metal casting and more particularly to novel structures combining a pouring gate and a riser in connection with metal casting molds.

In making a metal casting by filling a mold withliquid metal there are certain principles which are used in order that the finished casting may be made of sound, clean metal.

9Claims. 22-134) Accordingly, it is an object of the invention to efi'ect important economies by reduction'of the amount of metal required for pouring each casting, thus reducing melting costs and also the proportion of, metal which must be cut from the casting in the form of gates and'risers and subjected to remelting, with the usualconcomitant losses and deteriorations.

In order that the metal maybesound ,it is necessary that the familiar change in' volume with change of state be compensated for. In almost all of the commercial alloys there is a decrease in volume accompanying the change from the liquid to the solid state. In order to prevent this phenomenon from leaving unsound and spongy sections in the casting it is necessary that a reservoir of liquid metal be available as the casting freezes, and that this be connected to the casting in such a way that, immediately after the mold cavity is full, the casting freezes progressively toward this reservoir, or riser. The riser, of course, must be the last to freeze ofl. Liquid metal, when it is available, will flow into the intercrystalline cavities of contiguous metal which is freezing off and feed it, thus I preventing any'difiiculty from shrinks."

This principle may perhaps be made more clear by presenting it as follows: If an irregular. mold cavity is filled with metal which shrinks on freezing, and the metal is allowed to freeze, the heaviest sections of metal, which are the last to solidify, will be full of characteristic shrinkage cavities. In the method with which I am here concerned a sound casting is assured by making this shrinkage occur outside the casting proper, that is, by putting it in a riser. This riser must be attached directly to the casting or by a heavy connector. If too lighta connector is used it will freeze off before thecasting proper, and the riser will not have an opportunity to perform its function. To the same end the riser pref.-

erablyshould be located and designed so that This metal,

preferably, should not be allowed to run through the hottest metal is in the riser.

Another object of the invention is to produce uniformly sound castings of high quality. Another object-of theinventionis to simplify the pouring and gating of molds for casting.

Another object of the invention is to provide a pouring gate which will effectively skim the metal cast into the mold.

Another object of my invention is to so desig a gating arrangement that the metal occupying the downpour gate when themold is full will function integrally with that in the riser to feed the casting as it freezes.

Another object of the invention is to effect important economies by reduction of the amount of metal required for pouring each casting and I thus reducing melting costs and scrap losses.

Other objects of the invention will ap ar from the following specification and the accompanyingdrawings.

In the preferred embodiment of my invention, I provide a combined gate and riser unit which maybe assembled and used as a unit and-applied to various molds.

.A gating arrangement which has the basic essentials for making sound clean castings has (1) a down-pour gate; (2) passage from the gate into the mold cavity having a choke or skim bob, this passage designed, wherever possible, to

allow the metal to run into the bottom of the mold andrise therein, thus preventing turbulence with accompanying trapped air and *formation of oxide films; (3) a riser connected directly to the mold cavity through a wide passage; and .(4) the riser and the passage so related to the mass of. metal in the riser as toavoid freezing of the metal in the riser and in its connection to the casting until after the freezing of the casting itself.

In the accompanying drawings I have shown a preferred embodiment of my invention, and in the following specification I shall suggest various modifications thereof. It is to be understood that these are not intended to be either exhaustive or limitingmf the invention, but on the contrary' are chosen for the purpose of illustrating the invention, in order that others skilled in the art may so fully understand the inventhrough the combined gate and riser and portion of the connected mold;

Fig. 2 is a top plan view of the unit of Fig. 1; Fig. 3 is a vertical section taken on line 33 of Fig. 2;

Fig. 4 is a sectional view similar to that of Fig. 1, butshowing a modified unit embodying the invention;

Figs. 5 and 6 are diagrammatic sectional views showing'in comparison the metal necessary outside of the mold in the conventional practice and according to my invention respectively;

Figs. 7 and 8 are views similar to Figs. 1 an 3 respectively, but showing another modified form of the invention; v

Fig. 9 is a fragmentary view in horizontal section showing a twin mold embodying the invention; and

Fig. 10 is a view similar to Fig. 9, showing a multiple mold embodying my invention.

Referring first to Figs. 1 to 3 inclusive, I have shown at H) a fragmentary portion of a plaster mold designed, for example, for casting aluminuin 0r bronze. At the end of this is an opening ll through which the molten metal is fed into the mold cavity l2. A cavity of the size shown will ordinarily be provided witha core l0. Connecting with the opening ii, I have formed the .end of the mold with a recess l3, which in this case constitutes a part of the combined gate and riser when the mold isassembled with the gate and riser unit as more fully described below.

The gate and riser unit shown in pouring position in these figures consists of two separate channel portions l4 and I5, forming the outer portion of the riser and gate respectively and the former adapted to register with and form a continuation of the recess I3. The portions i4 may collect on thesurface of the molten metal and fiow with it into the pouring gate.

In the use of this device the metal is poured into the funnel at the upper end of the pouring gate channel member l5 through which it fiows down behind the separator l9 and through the opening 20 into the riser channel 13 and thence into the opening 1 l and finally into the mold cavity I2. As the metal rises in the mold cavity, it rises, of course, correspondingly in the riser channel l3l4. When the mold is finally filled and the pouring stopped the level of the metal will be at the same height on both sides of the separator l9 and advantageously close to the top of the channels I4 and I5 so as to provide a head" or hydraulic pressure on the metal within the cavity l2.

As the metal within the mold cavity l2 chills and freezes, its contracts, as already described above. So long as the metal in the riser channel l3l4 and in the opening ll remains molten and connected with the casting by a channel of molten metal, such metal will be available to feed the inter-crystalline cavities of the metal as it freezes ofi, and thus spongy portions and other imperfections in the casting can be avoided.

. Due to the relatively large opening shown at H, and due to'the fact that this opening II is surroundedby molten metal, both on the inside and the outside of the mold, the metal in the opening ll does not freeze until after the castand I5 are made of a refractory insulating ma- .terial. In most cases I find it advantageous to make these of a porous fully calcined plaster or other material with relatively high insulating value.

These channel parts [4 and I5 are held together in assembled relation and given additional strength to resist the weight and impact of the poured metal, and protect them against clamping forces and shocks to whichthey may be accidentally subjected, by the sheet metal sections lB-Il clamped together to form a casting for the combined gate and riser by means of the U- clamps I8, which are made of resilient steel and driven over the projecting edges of the casin members Iii-41.

Clamped between the members l4l5 and in this case extending betweenthe sheet metal sec 'tions lS-i'l is a separator IQ of a refractory sheet material, preferably of an insulatingnature so that it does not conduct heat away from the mass of metal in the gate and riser unit; I have found it advantageous to use for this separator IS a sheet of asbestos paper. Near the bottom of this separator I9 is a relatively small opening 20 through which the metal must pass from the pouring gate into the riser and before passing into the mold; thus, this partition l9 acts as a skimmer or choke to keep the metal clean and to hold back any dross or oxides, etc., which ing; and likewise, due to the insulation of the column of metal in the combination pouring gate and riser unit, metal in the riser does not freeze until after the casting and the connector II.

I should like particularly to emphasize that with my arrangement the metal finally occupying theriser is the hottest present. This is true for two reasons: (1) this riser is finally filled up with the last metal to be poured from the ladle, and (2) the metal in the riser has been cooled ofi by flowing through any portion of the mold. Also, with 'my arrangement it is possible to first introduce the metal into the mold through a low opening therein, and let it rise gently in the mold cavity, thus preventing the entrapping of air and the formation of oxide films which are the results of turbulence.

I find that my castings are extraordinarily clean and free of dross because the metal is so effectively skimmed by flowing through the slots I have provided. 1

It is important in obtaining these results that the riser and the gate are, as shown in the drawings, in close heat-exchange relation and together are insulated from the outside atmosphere.

metal poured into the pouring gate is added to the heat of the metal in the riser itself, thereby serving to delay the final freezing of the metal in the riser; and, once the pouring is stopped, the

two channels continue to act together as a single riser and in this way the metal left in the pouring gate replaces metal which otherwise would have to'be accumulated in the riser and the total amount of metal poured for each casting is thus substantially reduced with corresponding reductions in melting costs, in the capacity of melting and pouring equipment required, in the number of castings which can be made in one pouring and in the losses and deteriorations which occur upon reclaiming and remelting of the gates and risers. Moreover, the recovery of the gatesand risers and their removal from the final casting is simplified. Thus,

by the use of this invention there results at once 8 very substantially reduced cost and improved quality of casting.

In- Fig. 5, I have illustrated graphically the saving achieved by my gate and riser combina- L tion over a typical conventional arrangement. The closely cross hatched area shows in cross section the amount of extra metal needed to fill the conventional arrangement which is saved by my present invention. r

In Fig. l, as described above, I have used a recess in the outer surface of the mold itself to serve as a part of the riser channel. When the application, Serial No. 87,086, filed June 16, 1936,

it may be more desirable to construct a .complete unit which is merely clamped to the end of the mold with its opening ll registering with the corresponding opening into themold cavity.-

This I have shown in Fig. 4. In this case the construction is similar to that of Figs. 1 to 3 excepting that the channel member Ha for'the riser extends down as a complete mate for the channel member l5, thus making a pouring and riser unit complete in itself even before attachment to the mold. Such a unit may be used with plaster molds, with sandmolds, with permanent molds or in any case where a gate and riser should otherwise be provided. I

In Figs. 6 and 'l, I have shown another embodiment of the invention wherein-the connector between the riser and the mold cavity is in the form of a relatively long vertical slot llb; and in this instance the partition l9b between the gate and riser is pierced at several points by openings 20, 20', 20". Other parts shown in these figures are similar to those shown in Figs. 1 and-3 and are similarly numbered.

With many castings the design may be such that better results can be obtained by filling and feeding the mold cavity through a connector or connectors extending over a considerable distance. In such case it is very advantageous to use a series of openings as shown in Figs. and 8. This enables the top parts of the casting to be filled with hot metal flowing directly through the upper opening or openings as the level of the I metal rises in the mold, rather than by metal which has been cooled off by having first to .fiow through a lower opening. Thus the casting may be poured at substantially lower tempera-' ture without danger of the metal freezing on in the mold before the mold is entirely filled.

It will be obvious that by changing the number and position of the openings in the dividing partition it is possible to meet very easily the geting requirements of a great variety of casting designs. regulated by merely varying the size of the opening or openings in the partition. Funnels of a single design or a few standard designs and sizes can thus be used on a great range of applications. '75 of dimensions adapted to hold the metal there- The rate of flow of the metal can be In Figs. 9 and 10, I have shown two examples of the manner in which the invention may be adapted to plural castings. This arrangement has the further advantage that a single pouring funnel 150 or lid may be connected directly to and arranged directly adjacent a plurality of molds arranged in 'a single unit with a plurality of risers for the several castings, or with a common riser communicating with theseveral molds, all of which may be poured in a single operation. By reason-of the common gate or common riser and gate, the amount of metal required for casting is thus further reduced; and,

' by reason of the proximity of the several risers and central position of the gate and riser unit between the mold cavities, there is a greater economy of heat in gate and riser unit which permits a reduction in the volume of metal required for each riser, thus eflecting still further economy.

Although I have shown only a fragment of each mold with a single gate and riser unit, it

, will be understood, of course, that for many castings gates and/or risers will-be required at a plurality of positions distributed about the castings. the standard units may be applied to openings at any or all of these positions and may serve as both gate and riser or as' riser alonei. e.,

metal may be poured into all or less than all of the units provided. Where the unit is used solely as a riser the central partition I9 may be omitted, as its function is not then required,

although there is no objection to using the unit in exactly the same form as shown.

- It will be obvious to anyone acquainted with I gating practice that the relative. proportions of the channels on the sides of the partition i9 may be varied somewhat according to the requirements of particular castings, andthat no fixed ratio is necessary to effect the purposes of the invention. It -will be advantageous, however, to keep the riser channel as large in proportion to the gate channel as is consistent with convenient and satisfactory pouring of the metal.

What I claim is:

v .1. A combined pouring gate and riser unit for casting molds which comprises a pair of channeled insulating members of refractory material adapted to fit together with the sides of their respective channels engaging one another, one of said members having its channel open at its upper end to form a pouring funnel, and the other of said channels having an opening near its lower end adapted to communicate with the cavity of a casting mold and of dimensions adapted to hold the metal thereof molten until after freezing of the metal in the mold, a longitudinal partition between said members adapted to separate their respective channels but having a low opening near its lower end through which molten metal may flow with a skimming action, and a jacket adapted to hold said members together and augment their mechanical strength.

2. A combined pouring gate and riser unit for casting molds which comprises a pair of channeled members of a calcined plaster of Paris composition adapted to fit together-with the It is an advantage of my invention that.

of molten until after freezing of the metal in themold, a longitudinal partition of asbestos paper between said members adapted to separate their respective channels but having a low opening near its lower end through which molten metal may flow with a skimming action, and a jacket adapted to hold said members together and augment their mechanical strength.

3. A combination pouring gate and riser unit for casting molds which comprises a channel part of refractory thermal insulating material having an opening at its upper end adapted to receive molten metal .poured therein and an opening near its lower end through which it communicates with a cavity of a casting mold to feed molten metal thereto and of dimensions adapted to hold the metal thereof molten until after freezing of the metal in the mold, and a longitudinal partition in the channel of said part dividing it longitudinally into a pouring gate and riser, said partition having low heat capacity and low heat conductivity'and having a narrow opening near the bottom of said channel through "which molten metal must pass in flowing to the mold cavity and the riser from the pouring gate.

4. In combination with a casting mold, a pouring gate, a riser close to said pouring gate, communicating therewith through a low opening adapted to skim molten metal flowingtherethrough, and communicating with the mold cavity by an opening much larger than the skimming opening and of dimensions adapted to hold the metal thereof molten until after freezing of the metal in the mold, said riser and pouring gate being in close heat-exchange relation with one another and together insulated from external cooling.

5. A combined pouring gate and riser unit for casting molds which comprises a pair of channeled members adapted to fit together with the sides of their respectiv channels engaging one another, one of said members having its channel open at its upper end to form a pouring funnel, and the other of said channels having an opening near its lower end adapted to' communicate with the cavity of a casting mold and of dimen-. siOns adapted to hold th metal thereof molten until after freezing of the metal in the mold, and a longitudinal partition between said members adapted to separate their respective channels but having a low opening through which molten metal may flow with a skimming action.

6. In combination with a casting mold, a combined gate and riser unit adjacent to said mold and comprising a channeled member having its upper end open for receiving molten metal and its lower end closed from the atmosphere but communicating with the interior of said mold through an opening of dimensions adapted to hold molten metal therein until after freezing of the metal in the mold, and a longitudinal partition at one side of the channel having at least one'low'opening therein through which metal a may pass in its flow from said channel to the interior of the mold,

'7. The combination as defined in claim 6, in which metal receiving cavities extend beyond the said opening on both sides of the partition, whereby heat of the metal around the opening tends to keep open a communication of liquid metal from side to side through such opening.

8. In combination with a casting mold, a combined riser and gate unit having a channel therein open at the top and provided with an opening for communicating with the mold, the shortest diameter of said opening being not substantially less than the thickness of the metal part to be.

cast thereby, and a thin perforated longitudinal partition of refractory sheet material dividing said channel longitudinally, wherebyj metal poured on one side of the partition as into a pouring gate is skimmed by flowing through said perforations before entering the casting mold.

9. In combination with a pluralityof casting molds, a combined gate and riser unit adjacent .to all of said molds and comprising a channeled member having therein a pouring channel common to said several molds open at the top to form a pouring gate and closed at the bottom, but having an opening communicating with the interior of each mold, said'channeled member being positioned between and close to said molds, whereby the metal in said channel and openings may remain liquid until the metal in the casting has substantially solidified, and being divided by a tubular partition open at its upper end and having a low opening near its lower end, and spaced from the outer wall of said channeled member whereby to providea peripheral riser surrounded by and communicating with the several molds MORRIS BEAN.

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