US1863371A - Apparatus for casting - Google Patents

Description

June 14, 1932. GREENE 1,863,371

APPARATUS FOR CASTING Filed April 9, 1930 2 Sheets-Sheet 1 INVENTOR fl/berf f, 6re =ne ATTORNEYs June 14, 1932. E, GREENE I 1,863,371

APPARATUS FOR CASTING Filed April 9. 1930 2 Sheets-Sheet 2 iNVENTOR fl/berf E. reene ATTORNEYS Patented June 14, 1932 PATENT OFFICE ALBERT E. GREENE, F MEDINA, WASHINGTON APPARATUS ron cns'rme Application filed April 9, 19 30. Serial N0. 442,795.

This invention relates to casting and has for an object the provision of an improved apparatus for molding articles of various configurations. More particularly the invention contemplates the provision of an improved apparatus forcasting articles whereby articlesfree from internal defects maybe rapidly and economically produced;

Another object of the invention is to provide an improved apparatus for casting articles of various shapes by a continuous mechanical operation, the medium constituting the charge being poured either continuously or intermittently into a series of successively presented molds, allowed to harden and thence ejected from the molds, all by means of a mechanism, or a combination of mechanisms, under the control ofan operator.

The invention further contemplates the g0 provision of an improved apparatus for making metal castings having a substantially uniform density throughout their mass, particularly iron and steel balls, ingots and billets. The apparatus is especially suitable for man- 2.', ufacturing metal balls for use in grinding mills. p

Accordin to some heretoforecustomary practices of producing castings, and more particularly iron and steel balls for use in oreyor'rock crushing mills, the mold is composed of two complementary sections,- each section having a series of depressionsjcorresponding in size and shape to a half-portion ofthe casting to be produced.- These depres- Ss sions', which are semi-spherical in the case of iron and steel. balls, are connected byjshort channels, the end of'on'e ofthesechannels opening into an end-face of the mold section, such'that when-the two sectionsof the mold i 40 arebrought together the channelsiprovidean opening for theintroduction of a charge "0f-- molten metal. Afterthe"metal" ha"s been poured and has been allowed suflicient time toharden', the mold is se'parated-andthe;cast ing is'removed. This casting'consists in effect of a series of balls connected together by short: metal pipes of small diameter, or gates, which have to be cut away in a finishing operation.

This mode of producing balls is objectionable in several respects: First, during the introduction of metal Within the mold pockets or blow holes tend to be formed by gases generated and entrapped Within the mass and by the shrinkage of the metal due to its sub,- sequent unequal cooling; and since the head of molten metal, especially with reference to the uppermost balls, is usually insuflicient to break down the pockets so formed, balls are often produced which are too light for eflective use in grinding mills and subject to breakage when exposed to the severe shocks attendingsuch use. Second, the operation is usually carried out manually which is necessarily slow and expensive. And, third, the removal of the pipes or gates which connect the balls and the subsequent remelting of the recovered scrap are nonproductive operations consuming considerable time and consequently increasing the cost of manufacture;

In order-to overcome these objections, the apparatus disclosed in the present applicationhas been devised. This apparatus consists broadly of a mechanism adapted to produce castings havinga uniform density throughout 'their mass and having no connecting pipes, or in any event very short'ones. In its more complete embodiment, the invention consists of a continuously operating mechanism arranged to produce castings free from internal defects by an entirely automatieoperati'on. More particularly the apparatus' includes-a turnace, preferably of the electric induction type, for furnishing an 1n- 1 eXhausta-ble supply of molten'materiahfor example 'iron'or steel obtained'by the-reduction of'ore or the melting ofscrap'. The furpace structure includes a heating chamber in which the reduction of the ore or scrap takes 4 -place, and a pouring basin adapted to actas a reservoir for the molten metal which it receives from the heating chamber; or the basin may itself form an integral part of the heating chamber. From the pouring basin the metal charge is fed downwardly thru a nozzle into a series of molds which are successively brought beneath the nozzles. These moldswhich may be chill molds composed of metal, such as iron or steel, or sand molds held in metal framesare preferably mounted on a wheel, a belt, or a chain to move in an endless path and in a direction, at one portion of their cycle of movement, corresponding generally to the direction of flow of the metal stream at which time they are caused to assume a position in stacked relation. Thus as the, metal is being continuously poured, the stack is moved progressively downward and molds are added to the stack above and subtracted from the stack below. In order to avoid intersection of the metal stream by the edges of the molds as they move into a position beneath the nozzle the molds are made up of two complementary sections, or half-molds, normally biased apart by springs or other means. The sections are recessed in accordance with the configuration of the casting to be produced the recesses opening to the top and bottom surfaces of the molds. In the manufacture of metal balls the recesses are so formed that the balls are cast substantially tangent to each other with out any connecting pipes, or pipes of such inatppreciable length as to make unnecessary a nishing operation to remove the burrs when the castings are broken apart at their constricted point of junction, which may be referred to as the neck. As the sections pass under the nozzle they are arranged to be closed to surround the stream. The recesses of the-molds being in communication with each other the stack of molds together form in eflect an elongated chamber for confining a body of fluid metal. The stack is progre's'sively lowered, the molds being maintained closed, at a rate of travel so correlated to the rate of discharge of the nozzle that the average level of fluid metal within the chamber remains substantially constant. Asthe stack is moved downwardly, the average level of the fluid metal remaining constant, thecharge within the individual molds is subjected to increasing pressure resulting from the increasing metalstatic head. Although the charge may have chilled on its outer surface immediately upon deposition within the mold, the still liquid or plastic inner portion of the casting tends to distribute itself uniformly throughout the mass breaking down any gas pockets and filling in allshrinkage cavities. Movement of the molds downwardlycontinues until they have reached a predetermined position beneath the fluid. level in the stack, at which position the chilled casting is separated from the string of castings which are still contained within the molds above it and which may still be in varying conditions of plasticity. One manner of accomplishing this separation consists of providing means for swinging the sections of the mold to open position and extending an obstruction into the path of travel of the casting to deflect and snap the casting off at its neck. Another manner of separating the castings is to cause one mold to be shifted relative to its adjacent mold, thus severing the castings at their neck while the temperature of the metal is sufiiciently high'to ofier relatively little resistance to shear. It is important to note that the neck of metal joining the castings can be more easilysevered at the weak point of temperature slightly below the congealing point. By increasing the rate of discharge of the nozzle it is possible to increase the rate of travel of the molds consistent with the initial temperature and the physical characteristics of the metal being poured, the governing consideration being that the casting shall have attained a suflicient degree of hardness on its circumference to retain its shape by the time it reaches ej ecting position. Nor is it necessary that the charge be poured in a continuous stream, but

it may be deposited by an interrupted flow.

The temperature will of course depend upon the characteristics of the metal being poured. In the case of steel a quite high pouring temperature is ermissible without danger of the metal lea ing out between the contacting faces of themold sections and between the joints formed b the abutting surfaces of adjacent molds. When cast iron of comparatively high melting point is being poured its temperature must be regulated accordingly and an excess pouring temperature is less desirable from this standpoint. By proper control of the temperature a very small stream may be poured without solidification of the metal before it reaches the mold and in this way it is possible to pour continuously a stream of metal into castings of small cross sectional area.. For example, the stream may be so regulated thatittakes two seconds to The expression average level with reference to the fluid material within the chamber defined by the stack of communicating molds is advisedly used for the reason that. only in the case where the recesses of the molds have equal cross-sectional dimensions throughout their length will a uniform flow of material produce a uniform increase in the height of the column of material within the chamber. here the recesses have unequal cross-sectional dimensions throughout their length it necessarily follows that, while a uniform flow of material will maintain a constant average level, the instantaneous level of the material within the chamber will vary owing to the fact that greater amounts of material are necessary to fill the'expanded portions of the recess than are required to fill its more constricted portions.

While the apparatus is particularly described in connection with the casting of iron and steel balls, billets, ingots and bars, it will be understood that the invention is not limited to the use of these metals or the production of these articles. The molds may take any desired form depending upon the configuration of the casting sought.

The invention will be better understood from the description which follows, reference being hadto the accompanying drawings, in which:

Fig. 1 shows in side elevation one embodiment of the invention in which split molds are arranged about the circumference of a revoluble wheel, certain parts being shown in section;

Fig. 2 is a top sectional view of the apparatus shown in Fig. 1;

Fig. 3 is a front elevation of the apparatus shown in Fig. 1;

Fig. 4 shows a side elevation of another advantageous embodiment of the invention in which the two-part molds are carried by an endless chain or belt; and

Fig. 5 is a top plan view on the line 55 of Fig. 4.

Referring now to Fig. 1, in order to insure a constant supply of molten metal there is provided an electric scrap or ore melting furnace 1, which may be of the are or induction type, having a pouring basin 2 which is lined with an acid, basic or neutral refractory such as silica, dolo'mite or chrome ore. Communicating with the bottom of the basin is a relatively long nozzle 3 having a valve, operable by hand-wheel C, for determining the rate of discharge of the nozzle. This nozzle may consist of a metal pipe provided with an internal lining of some heat refractory material such as fused silica. The basin may be raised and lowered, to permit vertical adjustment of the nozzle, by means of a wedge block 4 having a screw member 5 threaded therein for sliding the wedge block relative to a tapered bearing block 6 upon-which latter block the basin 2 is supported. The basin may also be capable of lateral displacement by means not shown.

Located below the furnace and in adjacency thereto is a pair of spaced standards 7 supporting within suitable bearings a rotatable shaft 8. On this shaft is mounted a wheel 9 of relatively large diameter and adapted to be driven in a clockwise direction, as indicated by the arrow in Fig. 1, by means which may comprise an endless chain or belt 10 connected to a low-geared variable speed motor M, such driving mechanism being merely suggestive. Mounted on the circumference of the wheel 9 and preferably attachable to and detachable therefrom by means of bolts 11 is a series of split molds 12 made up of two sections 12a, 121). These molds rest in abutting contact and each section is carried on an arm 13 adapted to swing about a pivot 14 to move the section into tight contacting relation with the face of its complementary section forming a vertically closed or fluid-tight mold. Between the arms to normally hold the sections in spread position is a steel spring 13a. The contacting face of each section in this embodiment,

of the invention is recessed to provide a semibrought together form a pocket corresponding in size and shape to a grinding ball and having communication with the exterior of the mold. The edges 15a of adjacent molds lie approximately in a common plane which is almost, but not quite, tangent to the circumferences of two adjacent spherical recesses, thus permitting the casting of a series of balls connected together at their approximate point of tangency.

In order to prevent the sections of the mold when they are swung open from binding against the sections of the adjacent closed mold, their top and bottomsurfaces are chamfered as indicated at 16 in Fig. 3, the degree of chamfer necessarily depending upon the radius of the are described by the sections 12a, 12?) about their pivots 14 but in any event not being appreciable. Each of the sections carries a radially extending lug 17 so as to provide a pair of spaced projections on the outer surface of a mold 12'. Extending for a portiontof its length in adjacency with the outer arcuate surfaces of the molds on the circumference of the wheel9 is a guide plate 18 having a slot 19 terminating at its upper end in a tapered throat defined by the edges 20 opening to one end of the plate and so arranged as to engage the lugs 17 of the complementary sections 12a, 12b-to close the sections together as the wheel is rotated. The I ISI tween the lugs 17 and pry the mold sections apart if for any reason the sections should stickso tightly that the spring 13a is unable to separate them. The plate 18 is supported by a pair of legs intermediate which extends a trough 23 for leading the hardened castings away. The trough has one end projecting into the path of movement of the molds but is of such breadth as to extend between, without contact-ing, the sections 12a, 12?) when they are in open position.

This apparatus is arranged to operate as follows: A charge of metal having been introduced into the furnace 1 and heated to a temperature above its melting point, the position of the nozzle 3 is adjusted vertically by means of the screw member 5 which operates the wedge block 6 to raise and lower the basin 2 to which the nozzle 3 is attached. The distance of the nozzle above the mold is variable in accordance with the size of the stream of metal being poured. which in turn determines the amount of heat dissipated during pouring and hence the consistency of the metal stream. By reason of the heat-resisting property of the materials composing the nozzle it is possible to lower it to a considerable depth within the mold stack. This conducts the molten material to a position closely adjacent the level of the deposited metal within the mold, avoiding splashing and preventing contact of the stream with the faces of the mold sections.

A previously formed casting or a refractory block is initially placed into one of the molds 12 to act as a stopper for the molten charge, which if introduced while all the molds are empty would run out thru the recess of the lowermost mold of the stack. The valve controlled by handwheel C is opened to the desired extent and a stream of molten metal flows thru the nozzle 3 into the path of the molds 12. The wheel is rotated slowly in a clockwise direction by the chain or belt 10 connected to motor M, the travel of the wheel being so correlated to the rate of discharge of the nozzle that the average level of the fluid metal in the stack of closed molds remains substantially constant. As the wheel continues to revolve the open molds pass to a position beneath the nozzle 3 without intersecting the continuously flowing stream and are then brought together against the action of the spring 13a to form a closed mold by reason of the lugs 7 riding against the converging edges 20 of the tapered throat in guide plate 18. The stack of closed molds rest in tight abutting relation and their communicating recesses define an elongated chamber for confining a body of the molten metal. A mold having been filled with acharge ofmetal introduced through the opening 15a is moved progressively downward both sections being clamped'in fluid-tight contact by reason of sliding engagement of the lugs 17 within the slot 19. By the time the mold has moved a short distance below the liquid level the metal charge contained therein will have congealed on its surface precluding any tendency of the metal to run out between the joints of the mold although the metal may not be frozen through and feeding of the metal may be proceeding. The level of the molten charge in the slowly revolving stack of molds remaining approximately constant, the head of metal as the individual molds move downwardly necessarily increases, so that by the time a mold has reached a position at which its contained charge has solidified only to a slight depth on the surface of the casting where it contacts with the walls of the mold this head is sufiiciently great to break down any gas pockets which previously may have formed within the casting.

During the progress of the stack of molds downwardly the temperature of the deposited metal falls until at a certain distance below the level of the confined fluid metal the temperature will be below the solidifying point but in a condition which offers little resistance to separation of the balls. Further movement of the wheel 9 brings the lugs 17 of the mold sections into engagement with the wedge-shaped tongue 22 which pries the sections of the mold apart to release the hardened casting, the arrangement of the expanded portion 21 of the slot 19 being such that the lugs 17 ride out of the slot due to the receding motion of the mold before the lugs reach its lower end. The casting is now free to break itself away from the adjacent casting and drop by gravity into the trough 23 altho the interior of the casting may still be in a fluid state. In order however to positively insure the removal of the casting in the event it should still adhere to the adjacent casting, the upper end of the trough 23 is extended into the path of movement of the open molds to rub against the released casting and deflect it into the trough. The trough may lead to an annealing furnace or other apparatus for further treatment, or to a receiving hopper.

While the embodiment of the invention just described is satisfactory from a mechanic. standpoint for carrying out the casting operation forming the subject of this invention, it is perhaps most suitable in plants where economy of floor space is not a vital consideration.

In Fig. 4 of the drawings there is shown somewhat diagrammatically another embodiment of the invention which possesses all the advantages of the apparatus just described besides lending itself to conservation of the floor space of the plant. In this construction two pulleys 31, 32 are mounted in a vertical plane one above the other and adapted to rotate in a clockwise direction, as indicated by the arrows, on shafts carried by spaced uprights 33. Motion is imparted to one of the shafts as, for example, by a variable speed motor M. An endless chain 34 made'up of elongated links 34 is trained over the two.

pulleys and preferably arranged to engage spurs 35 on the circumferences of the pulleys to insure a positive drive. Split molds 36, composed of two complementary sections 364, are each carried by an arm 37 mounted to swing about a common pivot 38 forming part of the chain 84, springs 39 located between the arms being employed to hold the sections open. The molds 36 are preferably each of a length equal to that of a link 34 so that when the links occupy a vertical position each mold rests in tight end-to-end abutting contact with the adjacent mlolds. The complementary sections 36a are-recessed to produce a casting of the desired configuration (in this instance a billet or ingot) and, as in the previously described embodiment, the re cesses extend to the top and bottom of the sections to provide openings, when the sec-' tions are closed together, for the introduction and passage of the metal charge. A lug 40 is carried by each of the sections on its outer face.

In order to swing the sections together to form a closed mold there is provided a guide W flowing metal.

plate 41, in construction similar to the plate 18 shown in Fig. 1, having a slot 42 opening to the upper edge of the plate through a tapered throat 43, the plate being fixedly supported by legs 45. The slot 42 has an expanded zone at its lower end and a wedge-shaped tongue 44 projects into this expanded zone. EX- tending between the legs 45 of the guide plate and projecting into the path of the mold sec.- tions at an elevation below that of the tongue 44 is a trough 46 adapted to bear against and positively eject the casting after the mold has been opened. The open sections of the mold permit free passage of the trough therebetween.

A nozzle 47, which may communicate with a basin forming a part of a melting furnace, substantially as shown in Fig. l, is arranged in a position to direct a stream of molten metal vertically downward in alignment with the openings in the molds 36 after the sections 36a have been swung together.

The operation of the apparatus just described is as follows:

The nozzle 47 is opened and a stream of metal flows vertically downwardly. As the pulleys 31, 32 are rotated slowly in a clockwise direction the chain 34 is moved by engagement with the spurs 35 tobring the open molds 4O successively beneath the stream of The sections 36a of the mold,

being normally retained in open position by the springs 39 so as to avoid intersecting the stream, are now swung together to form a closed mold for the reception of a charge of metal by reason the lugs 40 riding into en gagement with the edges of the guide plate defining the tapered throat 43. The mold receiving a charge at this juncture forms the uppermost of a series of communicating molds arranged in stacked columnar relation along one of the vertically extending passes of the chain 34. As the molds are moved slowly downward,'the speed of rotation of the pulleys being so regulated that the average level of the charge of fluid metal in the elongated chamber formed by the recesses of the communicating molds remains substantially constant, the lugs 40 are gripped between the sides of the slot 42 to hold the mold sections tightly preventing escape of the metal. The metal is gradually cooled but before it has reached a complete state of solidification the mold has been lowered to such an elevation below the liquid level that the pressure of the head of molten metal breaks down any pockets which may have been previously formed resulting in a casting of uniform density. Further movement brings the lugs 40 into engagement with the wedge tongue 44 which pries the sections of-the mold apart and re leases the solidified casting. The released casting is broken off by the raised end of thetrough 46 which projects between the open mold sections and away.

I claim:

1. Ina casting apparatus, a series of molds arranged to travel in a common endless path in a vertical plane, said molds having a recess therein opening to a surface of the mold disposed transversely of the path of travel of the molds and each mold being split in a substantially vertical plane'intersecting the recess to define two secti0ns,,said sections being pivoted for opening and closing movement, a spout for discharging a stream of molten metal downwardly, means for swinging the sections to closed position beneath the stream, andmeans for subsequently lowering the scenes of molds. v

. 2. In a casting apparatus, a series of molds arranged to travelin an endless path in a vertical plane comprising -a pair of mold sections each having a substantially vertical plane face provided witha recess opening through an end surfacerof thesection disposed transversely of thepath .of travel of the molds, a spout for discharging-a stream of molten material: downwardly,,:means for pivotally. mounting the sections to permit.

their. beingclosed together-under the stream.

of molten material; means for lowering ,the-

molds, and means, for subsequentlyopening' themolds.

the casting is conducted lab 3. In a. casting apparatus, a series of molds vidual-molds together form asingle clone gated chamber for the reception of a charge of molten metal, saidmolds being split in a substantially vertical plane through their recesses to define two sections, said sections being constructed for opening ,and closing movement, a spout fordischarging a stream of molten material downwardly and means for closing the sections under the stream for causing a charge of molten metal to be deposited in the recesses.

'4. In a casting apparatus, a series of molds arranged to travel in a common endless path and each having a. recess therein opening to the top and bottom surfaces of the mold, said molds being-so arranged in end-to-end abutting contact that the recesses of the indi- Vidual molds together .form a single. elongated chamber for the reception of a charge of molten metal, said molds being split in, a substantially vertical plane through their recesses to define two 'mold sections, said sections being pivoted for opening and closing movement, means for swinging the sections together under the stream for causing a charge ofmetal to be deposited in the recesses, means for lowering the series of molds, and means for subsequently separating the mold sections.

5. In a casting apparatus, a series of molds arranged to. travel in a common endless path tially vertical plane through the recesses so as to define two mold sections, means for pivotally mounting said sections, a spout for dis charging a stream of molten material, means for drivlng thecarrier, means for closing the sections as they pass beneath the spout, means for lowering the molds, means for subsequently opening the molds, and means for removing the casting from the mold.

In testimony whereof I aflix my signature.

ALBERT E. GREENE.

and each having a recess therein opening to the top and bottom surface of the mold, said moldsbeing so'arranged in end-to-end ab'uttingcontact that the recesses of the individual molds together form a single elongated chamber for the reception of a charge of molten metal, said molds being splitin a substantially vertical plane through their recesses to define two mold sections, said sections being pivoted for opening and closing movement, means for swinging the sections together under the stream for causing a charge of metal to be deposited in the recesses, means for lowering the series of molds,

and means for subsequently separating themold sections.

6. In a casting apparatus, a carrier movable in a single endless path, a series of molds mounted on the carrier arranged in end-t0- end abutting contact, said molds being provided with recesses opening to their top andbottom surfaces and being split in a substan? tially vertical plane through the recesses so as to define two mold sect-ions, means for pivotally mounting said sections, a spout for discharging a stream of molten material, means for driving the carrier, and means for closing the sections as they pass beneath the spout.

7. In a casting apparatus, a carrier movable in asingle endless path,a series of molds mounted on the carrier arranged in end-toend abutting contact, said molds being provided with recesses opening to their top and bottom surfaces and being split in a. substan-

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