US2459892A - Metal casting apparatus - Google Patents

Description

Jan. 25, 1949. s. L.. PALMER ET AL 2,459,892

METAL CASTING APPARATUS Filed Dec. 14, 1945 5 Sheets-Sheet l III III 'i'l Jan. 25, E949. s. L. PALMER ET Al. 2,459,392

METAL CAST ING APPARATUS 5 Sheets-Sheet 2 Filed Dec. 14, 1945 5% :Nw-:NTO s zdmfy L Palm BY Jagd 1% A8er/fes A RNEY Jan. 25, `1949. n s. L. PALMER ET AL 2,459,892

METAL CASTING APPARATUS Filed Dec. 14, 1945 5 Sheets-Sheet 3 INVENTORS 514mg L Palmer BY lag/d Ber/fes 15 ATTRgm l Jam 25, 1949.

s. L. PALMER ET AL METAL CASTING APPARATUS `5 Sheets-Sheet 4 Filed Dec. 14, 1945 VENTORS M 5ft/QS ftw ATTORNEY @muy Pm/ffm# BY Jagd 5 sheetslsheet 5 Filed Dec. 14, 1945 ATTORNEY Patented Jan..l25, 1949 UNITED STATES PATENT OFFICE METAL CASTING APPARATUS Application December 14, 1945, serial No. 634,934

(ci. ca -7o) 3 Claims.

This invention relates to casting machines and more particularly to casting apparatus of the closed split-mold type into which molten metal is introduced and cooled to produce cast shapes, the mold being opened and the casting ejected after solidiflcation.

Briefly, the invention provides improvements vin vcasting machines of the type comprising a vessel or receiver for holding a supply of molten metal to be cast and an initially closed mold which is in communication with the receiver and into which molten metal from the receiver lis pumped. Operation of the casting machine `invention also makes it possible, as a commercial operation, to standardize the shape, size and appearance of castings. Although the invention has been utilized for casting white metal alloys, for example, in the production of ybar solder, rods,

' etc., it is equally applicable for casting other metals and alloys, such as used to make weights, sinkers and the like.

In operating the machine of the invention, molten metal is introduced into the mold and chilled to form the casting under controlled conditions, the temperature and pressure being regulated during casting to bring about filling of the mold and to provide for shrinkage feeding as the metal cools and solidifies. The sequence of operations lperformed during the casting cycle is controlled by suitable electrical timing mechanism as hereinafter described.

The invention will be particularly described in connection with the casting of solder bars but it will be understood that this is merely illustrative of the invention and not limitative thereof. Other objects and features of the invention will appear from the following detailed description of one embodiment thereof taken in connection with the accompanying drawings, in which the same reference numerals indicate similar parts, wherein:

Fig. 1 is a vertical section view of the casting machine, illustrating diagrammatically the melting furnace, molten. metal-receiver, molds and electrical system for controlling the casting operations;

Fig. 5 is a detailed view in section of the splitmold, the mold being shown in open position;

Fig. 6 is a plan View of the movable mold cover;

Fig. 37 is a similar plan 'View of the complementary mold half which is held stationary during casting; v

Fig. 8 is a view in cross-section of the mold taken on the line 3 8 of Fig. `'l and looking in the direction of the arrows;

Fig. 9 is Van electrical diagram showing the layout of the general timing and control system.

Referring to the drawings, Figs. l and 2, the numeral I0 designates a furnace for melting pig metal I I from which castings are to be produced, the metal being melted on a hearth I2, suitably heated by a burner I4 arranged therebeneath, as illustrated in Fig. 1. Molten metal in the melting furnace ows from the hearth I2 into a receiver or vessel l5 through a charging spout or ladle I6.

A float il positioned in the melt I8 operates through'conventional mechanism, not shown, to control the fuel supply to burner I4, whereby a relatively constant amount of molten metal is maintained in the receiver I5 during casting.

Thermostatic control of the burner I9 is provided by the thermostat 20 which operates through associated mechanism 2| to vary the setting of the burner which in turn maintains the melt I8 at the desired operating temperature. Where it is desired to limit the degree of oxidation of the metal during melting, the atmosphere in the furnace is suitably controlled.

Molten metal is pumped from the receiver I5 to the casting mold, generally designated by reference character 22, through a manifold pipe line 2l by a submerged centrifugal pump 25, the pump being suitably supported while submerged in the melt and connected to the manifold, as illustrated in Fig. l. Excess molten metal entering the manifold is returned to the receiver through pipe 26, being discharged beneath the surface of the melt as shown at 2l. By this arrangement, a closed molten metal circulating system is provided whereby oxidation of the metal during casting is held to a minimum.

To operate the centrifugal pump 25, a variable speed motor 55 is suitably mounted over the melt on a supporting frame structure 3| and is drivingly connected to the vertically disposed pump propeller shaft 52, as illustrated in Fig. 1. For controlling the pressure oi.' the molten metal supplied to the mold from the manifold, a throttle valve 55 is placedin line 25. This throttle valve is operated by a piston actuated rod 55 working in a hydraulic cylinder Il. Fluid under pressure for actuating the piston in cylinder 51 flows through pipe lines 35 and 55 which are, in turn, connected to a pressure control valve 55, the control valve being operated electrically in accordance with the setting of the general timing and relay system shown schematicallyvin Fig. 4. The pressure of the molten metal flowing to the mold may also be varied by changing the speed of motor 35 using similar electrical timing mechanism. These two methods of pressure control may be used singly or in unison, as desired.

. The general arrangement of the mold and associated operating mechanism is illustrated in Fig. 3. The mold 22, which is suitably supported vertically, comprises a base or mold proper section 55 and a. complementary cover section 5| supported for movement into closed and open position. In the preferred form, illustrated in Fig. 3, the mold cover is hinged to the base l mold half 55 at its upper end, the mold base portion being rigidly supported while the cover is pivotally secured thereto as at 52. A

In theembodiment illustrated, water under appropriate pressure is utilized to actuate the moving parts of the casting apparatus and cool the mold, being supplied through pipe line 55 from a suitable source and discharged through line 55 after use. Cooling water is conducted from the su l line 55 to the mold halves 55 and 5I by pp y o the mold during solidiilcation of the casting fill.-

conduits 55 and 55 respectively, and from' the mold to the discharge line 55 by conduits 51 and 55, as illustrated in Figs. 2 and 3. A ilexible hose connection is used for water lines 55 and 55 to permit movement of the mold cover 5| during operation of the casting machine. Where it is 45 desired,I other and independent fluid pressure means, such as air, steam or oil,l may be used to actuate the moving parts of the casting apparatus, cooling water for the mold being supplied through a separate line.

For opening and closing vthe mold, a hy.- draulically operated cylinder 55 is utilized, as illustrated in Fig. 3. A piston rod 52 working in the cylinder 55 is pivotally connected at its outer end, by a pin 55, to the pair of angle sections 55 which are bolted to the mold cover 5| as shown in Figs.

-3, 5 and 6. Hydraulic fluid for actuating the piston is conducted from the control valve 55 to the cylinder by conduits 55 and 51. A similarly piston operated rod 15, working in the hydraulic cylinder 12, is provided to actuate the ejector pin 15r and eject the casting 15 upon opening the mold. Fluid pressure for operating the ejector-p in-actuatlng cylinder 12 is conducted through the pipes 11 and 15 which are connected to the control valve 15. Suitable handling, marking and packaging mechanism for the casting may be provided, such as illustrated diagrammatically at 55, 5| 'and 52 respectively, in Fig. 3.

'I'he -detail construction of the molds is illus-V trated in Figs. 5, 6, I and 8. The mold half 55 and hinged cover section 5| are each provided with a water cooled back portion which is designed to provide diilerential cooling between the upper and lower ends 'of the mold. The lowest tem- 4 perature is maintained at the top of the mold by introducing the cooling water at the upper end, as indicated at 55 and 55, and withdrawing it at the bottom, as shown at 55 and 55. Ther- 5 mostats 55 and 5 5 are placed in the outlets- 55 and 55, respectively, which operate to increase or decrease the amount of cooling water admitted in accordance with the temperature variation of the water leaving the mold'. For example, when the temperature of the discharge water exceeds length, suitable bailles 55 are cast in the water cavity to direct4 the water flow in a zig-zag path downwardly through the cooling chamber, as indicated by the arrows in Figs. 6 and '1.

Molten metal during casting, is admitted at the bottom of the mold under low pressure to avoid splashing and squirting-the mold being filled as the pressure in line is increased by closure of' valve 55. Air vents 52 are provided near the top of each mold cavity as illustrated in Figs. 6

25 and '1, to assist in rapidly evacuating the mold of air when it is being illled. Where it is desired, a neutral or reducing atmosphere may be employed in themold, as for example, when casting oxygen-free metal. As the molten metal rises in the mold, it cools due to contact with the mold,

the coldest metal Ibeing always at the top of the mold. By utilizing the mold construction and arrangement illustrated, the temperature gradient during cooling of the cast metal is such that the directional solidication of the casting is opposite to the iiow of the metal entering the mold.

As the mold nils and solidlilcation progresses molten metal at the lower end of the mold, being under maximum pressure, continues toA flow into ing shrinkage voids produced as the freezing progresses downwardly to the end of the mold. This results in the production oi.' a casting which Ais free from shrinkage voids. After the metal in the mold has completely solidiiled and there is no further flow of the metal to the mold cavity, freezing progresses slightly into the entry port or gate 55. A similar port is provided at the lower end of each mold cavity 55, as shown in Fig. 7. The

mold illustrated comprises only two pockets or mold cavities 55, with associated ejector pin means 15, but it will be appreciated that this is merely exemplary and that molds may be used, in practicing the invention, having any desired number of cavities depending upon the type of castings being made, sizes, and capacities required.

Operation of the various casting elements is electrically controlled, the general layout oi' the system being shown in Figs. 4 .and 9. Four time u' switches |5l, |52. |53 and |55 and six relays |55,

V7'0 scribed as follows:

Assume that the mold is 'closed with ejector pins 15 in retracted position flush with, and thus constituting a part of, the mold inner' wall, molten metal is ilowing under low pressure 7s through mammie u, and unie switches m,

' solenoid valve metal enters ,tire-:mold: cavities '90' through ports ilffrom the coupling member-Qnadapten .91, being deflectedthereignto bybaille, 98- as- .illustrated in F185. 5. and Asthe mold fills, pressure in the manifold 24 is. increased by. partial or. substantial closing of. ,they-alve 35., through .actuation of, the 40, to provldesulcient pressure .for ,iillins.,sollidifisation..shrinkage voids. Directionali-solidieation is -effected, by the 4cooling water circulated .freezing ofI thebar. at the ports 95.-,-

When the metal-in vthe, mold hasbeen completly ,solidified-the mold cover M iswithdrawn after the pressure .in-the manifold line 24 lhas the. receiver-l through the line 24 and adapter.

:91 itis deflected upwardly and againstthe ports 95 by thebaiiles V9.0, which are positionedin the adapter opposite the ports, as shown in Figs. 5 and' 7u By. this construction and use of the apparatus the. solidified sprue portion remaining in the ports y95, after the casting has been ejected, is quickly remeit'edfwhereby, upon the withdrawal .of .the ejector pins 15, molten metal is permitted to again flow through the ports 95 into the mold.

Upon closure of the mold, the hydraulic cylinder 1 12 is actuated tdcauseretraction Aof the ejector pins.l Thereafter the pressure of molten metal qwing in manifold 24 is increased, by operation of..I valvel 35, causing filling of the mold, thus starting a new cycle.

' Utilizing conventional electrical time switches and relays` connected as indicated by the diagrams, Figs. 4 and 9, theA proper sequence of oper- .ation of .the machine elements is provided. Utilizing the invention, solder.- bars weighing 11,52 pounds have been cast on a time cycle of l5 to.23 seconds. ;The cast bars were of uniform size and vshape-'and lthe maximum weight variation was le 'ounce` perbar. In thisconnection, it will be-appreciated that the time cycle may be varied to suit different metals and casting conditions.

The general timing control system, for operating the machine elements in proper sequence is illustrated in Figs. 4 and 9. Using a power line of 115 volts and 60 cycle, as indicated in the Wiring diagram of Fig. 9, a casting cycle is initiated by depressing the momentary-contact push button marked Reset, Fig. 9.

Current flowing through undervoltage coil A of relay |05 seals itself in through its normally open interlock B. Relay |06 being de-energized, a circuit is prepared through normally closed pole C for energizing the pressure control timer |0|. The pointer of the timer is at zero reading and, accordingly contacts E are closed so that the clutch coil F is energized and the pressure control timer starts timing. Clutch contacts G immediately close, maintaining current to the clutch coil F, after'the pointer of the pressure control timer leaves the zero station.

When the pre-set pressure control timer comes to the end of its time period contacts H are closed passing current through the relay coil I picking up the relay |01 whose normally closed pole vJ through the back of the mold' vhalves,4 as previouslyv described, tocause final opens de-energizlng coil K of relay |09. This ends the time period' controlled by the pressure control timer |0|. At the start of this timer, the normallyl 4open contacts Y of relay |09 were closed energizing the solenoid valve coil 40 in the circuit .PCV thereby closing the throttle valve whereby molten metal under high pressure is established in line 24 causing mold 22 to be completely lled. At the end of the pressure control timing period, the solenoid coil operating the throttle valve 35 is de-energized, opening this valve and establishing low pressure in line 24.

n At the end of the pressure control timing period, relay |01 is energized and one of its normally open poles L energizes the clutch coil M of the mold timer |02. This mold timer immediately starts timing and continues to time as long as contactsl Hvremain closed. Contacts H' are maintained closed during the period the clutch coil F is kept energized. When the mold timer |02 starts to time, the solenoid coil of the mold -valve 65 is energized, through line connection MV, to hold the mold open. After the pointer of the mold timer |02 has moved through a pre-set time interval its contacts N close energizing mold relay coil O operating relay |08 whose normally closed pole P opens de-energizing the circuit to the mold solenoid valve 65 permitting the mold to close. 'I'he mold is held open for a pre-set time interval which starts to run at the termination of the pre-set time interval established by the i pressure control timer |0|.

lWhen the time interval controlled bythe pressure control timer terminates, another open pole contact Q` of relay .|01 closes energizing clutch coil R of ejector pin delay timer |03. This starts the ejector pln delay timer on its timing interval,

' the timer starting to run only when the pressure |03, its contacts S close energizing the clutch coil vcontrol timer |0| has terminated its timing interval. By adjusting the ejector pin delay timer.'

the time interval of delay between the instant the solenoid valve coil 65 is energized and actuation of the ejector pin solenoid valve 19 is readily controlled and pre-set.

Upon timing out of the ejector pin delay timer T of the ejector pin timer |04, and starting this timer timing. When the timer |04 starts to time, it energizes the ejector pin solenoid valve coll 19 in line EPV, through contact U which operates to move the pin to out position. De-energizing of this coil causes the ejector pin to be moved to in or retracted position. The ejector pin timer |04 controls the time interval during which the ejector pin is out, the interval being pre-set by adjustment of the timer |04.

At the end of the time interval controlled by this ejector pin timer, its contacts V close, energizing coil W of relay |06 whose normally closed pole X opens to de-energize the coil Z of relay ||0 whereby the circuit to ejector pin solenoid valve 19 is broken. Through the second normally closed pole of the ejector pin relay |06, the clutch coil of pressure control timer |0| is de-energized. The time-closing contacts H of the pressure control timer |0| open, after suicient time elapses to permit the pointer to move far enough toward zero position to allow these contacts to separate.

After this occurs, relay |01 is de-energized, and its two normally open contacts return to open position. This action de-energizes the clutch coils of the mold timer |02 and the ejector pin delay timer |03. Upon de-energizng of the ejector pin delay timer clutch coil and the pointer has returned toward zero position suillciently to contacts oi this relay are now closed automaticallystarting a newlcycle. Limit switches LSI, L82, LSI and LSI in the timers lli, III, III und I, respectively, are normally closed, being adapted to open when the pointer of the timing motor reaches full scale position, thereby protectlng the time switches from over travel with possible attendant damage to the instruments.

Utilizing the present invention to cast solder bars, no mold dressing is required, however, it will be appreciated'that when the use of mold dressing is necessary, suitable means may ,be provided for doing-this, tor example, byarranging to spray the mold with bone-ash slurry. or the like.

at intervals to prevent sticking.

While the invention is particularly adapted to the casting of white metals and lead alloys, it will be understood that the principles thereof are applicable generally to the casting of other metals and alloys which present problems similar to those encountered in casting white metal. Further it will be appreciated that various omissions, substitutions and changes may be made by those skilled in the art without departing from the spirit of the invention.

What is claimed is:

1. In a machine for casting metals and alloys having a vessel for holding molten metal to be cast, a split-type mold having a port for admitting molten metal thereinto, and a Lconduit for molten metal interconnecting said vessel and mold via.` said port, the combination with. said I. mold of a reciprocable pin which in retracted position is clear of the port and mold cavity and in extended position enters the cavity a sumicent distance to constitute'both a closure for the port and an ejector of the casting from the mold.

2.In a casting machine of the class described having a vessel for holding molten metal to be cast, a vertically-disposed mold oi' the split-type hinged at the top and with a port near the bottom for ingress of molten metal to the mold cavity, a pump in said vessel, a conduit interconnecting bination with said mold of a reciprocable mem- 4 ber constitutinga 8 said pump and port and returning to said vessel with a. valve in the return portion o! said conduit, and passageways in said mold so positioned as to eiiect progressive solidiiication of the cast'- ing from the top downwardly to the port when cooling fluid is circulated therethrough, the com- Dlrtf the mold Vinner will when in retracted position, and a combined port closure and castingl ejector when in extended position.

3. In' metal casting apparatus having a vessel for holding molten metal to be cast, a split-type mold, a pump, a conduit for molten metal having one end connected Ato said pump and. the other end open, both ends being positioned below the metal line oi' the vessel, said conduit comprising a molten metal supplyfsection and a molten metal return section both extending exteriorly of said vessel, and acoupling member providing a passageway for molten metal between slid supply section and the mold cavity. the combination therewith of a throttle valve in said molten metal return section having a valve operating mechanism and timing device associated therewith controlling the closing and opening of said throttle valve in accordance with a predetermined set-- ting of the timing device.

SIDNEY L. PALMER. LLQYD M. BDCKES.

REFERENCES CITED The following references are of recordy in the tile of this patent:

UNITED s'iwncs PA'rsN'ra Number

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