US2637079A - Centrifugal casting device - Google Patents

Description

May 5, 1953 A. J. KEMPPE CENTRIFUGAL CASTING DEVICE 3 Sheets-Sheet l Filed Sept. 16, 1950 INVHVTOR. ADAOLPH J. KEMP/"E uw v S mm ATTORNEY May 5, 1953 A. J. KEMPPE CENTRIFUGAL CASTING DEVICE 3 Sheets-Sheet 2 Filed Sept. 16. 1950 INVENTOR. ADOL PH J. KEN/PE BY f f Il A 7' TORNEY May 5, 1953 A. J. KEMPPE CENTRIFUGAL CASTING DEVICE 3 Sheets-Sheet 3 Filed Sept. 16, 1950 INVENTOR. ADa/ P# J. KEMP/DE BW A 7' TORNEY Patented May 5, 1953 UNITED STATES PATENT OFFICE CENTRIFUGAL CASTING DEVICE Adolph J. Kernppe, Santa Rosa, Calif.

Application September 16, 1950, Serial No. 185,195

8 Claims. l

rIhis invention relates to a centrifugal casting device.

The primary object oi the invention is to prow vide a centrifugal casting device which can be preset so as to heat a wax mold for a predetermined period, then to melt the metal for injection into the mold cavities, and then be automatically set into spinning operation by the molten metal so as to simultaneously release the first heating element and to trip a rotating device in such a manner as to spn the mold with the Crucible thereon in which the metal is melted, thereby to inject by centrifugal force the metal into the mold cavities.

Another object of the invention is to provide a device which can be preset so that the burn-out Inutile operates for a predetermined period necessary to meltthe wax out of a Wax mold and after the predetermined period to set in operation a crucible for melting the gold or other metal used in the casting, then utilizing the molten metal as a conductor ior actuating release mechanisms for disconnecting said currents and devices and releasing a preset spinning mechanism to spin the Crucible and the mold together and by centrifugal force transfer the molten gold or metal from the Crucible into the waX mold, means being provided to draw out gases or air or other matter trapped in said cavities.

l am aware that some changes may be made in the general arrangements and combinations of the several devices and parts, aswell as in the details of the construction there-of without departing from the scope of the present invention as yset forth in the following specication, and as defined in the following claims; hence I do not limit my invention to the exact arrangements andA combinations of the said device and parts as described in the said specification, nor do I conne myselfk to the exact details of the construction of the said parts as illustrated in the accompanying drawings.

With the foregoing and other objects in view, which Will be made manifest in the following detailed description, reference is had to the accompanying drawings for the illustrative embodiment of the invention, wherein:

Fig. 1 isa cross-sectional view of an illustrative embodiment of m-ycentrifugal casting device.

Iiig` 2 is a sectional plane view of the circular base and the spinning device therein.

Fig. 3 is a top plane view partly in section ofv my castingdevice.A

Fig. 4 is a cross-sectional View of the Crucible of my device.

Fig.v 5 is a sectional viewthrough the frame bars (Cl. .Z2-65.1)

of the device viewing the end circuit breaker and its contacts.

Fig. 6 is a sectional View through the frame viewing the end contacts on the end of the whirling shaft, and

Fig. 7 is a wiring diagram of the electric circuits of my device.

In its general organization my centrifugal casting device includes a spinning device I contained in a base 2, the shaft 3 of which carries on its top a whirling or spinning frame 4. On one end of the spinning frame is suitably supported a casting or wax mold 65 in operative relation to a Crucible l', At the other end of the whirling or spinning frame 4 is a counterweight 8 and suitable circuit breaker device 9 for the circuit control. A burn-out muille I I is mounted on a guide frame l2 so that it can be slid over the casting or wax mold 5, and held there by a suitable rei leasable catch device I3 to be tripped or released aiter a predetermined period.

A solenoid release device Ill mounted on the base 2 controls the release of the burn-out Inutile Il. Another solenoid release device i6 -controls the circuit breaker device 9. The entire electric circuit of the device being controlled by suitable timing device as shown in the wiring diagram in Fig. 7.

The spinning mechanism l in the present illustration includes a dat coil spring l l which has its outer end l il anchored to the wall IE! of the cylindrical hollow base 2. The inner end 2l of the spring il is anchored in a drive ring 22 around the shaft 3. On the shaft 3 is a substantially y rectangular collar 23 which is located inside of the drive ring 22. Generally tangential holes 24 extend from the outer periphery to the inner periphery of the ring 22 on opposite sides of the ring and each hole 24 has a ball 26 therein adjacent a side of the rectangular collar 23. This arrangement permits the shaft 3 to rotate freely in a contraclockwise direction viewing Fig. 2, but the collar 23 jams the balls B3 when the collar 23 is rotated in a clockwise direction so as to connect the ring and the collar together. The ring E2 and the dat spring il rest upon a partition plate El spaced above the bottom of the base 2. Ball. bearings 2S in the bottom and in the top of the base 2 suitably support the shaft 3 in said base 2.

The whirling or spinning frame includes a hub mounted on the top of the shaft 3. In the pre-sent illustration the hub 29 is on a reduced and threaded shaft end 3l held against the shoulder at the top of the shaft 3 by a suitable nut 3 32 in the top of the hub 29. A spinning shaft 39 extends from the opposite sides of the hub 29.

On one end of the spinning shaft 33 is a saddle plate Sil on which is mounted the casting mold 6 which includes the usual casing 99 containing the mold 31 with suitable cavities l2 usually lled with wax to conform to the contour of the gold or metal frame or part to be cast, for instance of a dental casting. This casing 36 is securely ixed on the saddle plate Sli and pressed against a partition disk 33 at its front. The partition disk 38 has an opening 39 near its lower portion for communication into the intake port @l of the mold cavities d2. In front of the partition disk 38 is the crucible 1 which is suitably mounted on the spinning shaft 39 and has its outlet 4f aligned with and leading into the intake port M of the said mold cavities 62. The crucible 1 includes an outside casing 46. This casing it is preferably a longitudinally split cylindrical casing suitably hinged on one side and clamped together around a Crucible chamber i1 of suitable refractory material. A heating coil i8 is placed within the casing 4S and around the crucible chamber l1 and is suitably connected to a source of electricity as hereinafter described. The crucible chamber l1 has an intake opening 45 at its end spaced from the partition plate 3S through which the metal to be melted can be introduced. The casing 6.9 is lined with a heat resistant lining 49.

A characteristic of the crucible 1 herein used is that an electric conduit system is provided in said crucible and has its terminals so exposed that the circuit is bridged by the molten metal in the Crucible chamber 1. This circuit system is connected by suitable wirings to be hereinafter described to the control solenoids which control the various release devices. In the present illustration a pair of terminals i9 and 5l are provided in the bottom or lowermost portion of the crucible chamber bi1. At least one of these terminals is insulated except for its exposed end. The ends of the terminals i9 and 5! inthe crucible chamber l1 are spaced from one another at a suitable distance so as to normally keep the circuit open. After the metal indicated by the circle 52 in the crucible chamber i1 is melted it flows toward the outlet of the Crucible chamber 41 because of the inclined bottom 53 of said crucible chamber and it bridges the gap between the terminal points i9 and 5l which through suitable timing release and devices, as shown in the wiring diagram, operate and trip the release mechanism to set the device into whirling or spinning.

A gate or door 59 covers the intake opening i9 of the Crucible chamber 91. This door 54 is lined with suitable heat insulating material and is supported on a cross-bar 55 on suitable spring hinges 51 for normally urging the door 54 in closed position.

On the other end of the spinning or whirling frame and on the other end of the spinning shaft 33 is supported a bracket 58 carrying a counterweight shaft 59. On the counterweight shaft 5S are the usual counterweights 8 which can be easily replaced and removed for the balancing of the whirling device. On the back of the bracket 58 are provided a plurality of contacts, for electrical circuit connections. In the present illustration there are two pairs of contacts. A pair of contacts or terminals 62 are connected by electrical lines 63, preferably concealed or attached to the adjacent whirling shaft 75 33, leading respectively to the terminals 49 and 5| in the crucible chamber 41. The other pair of contacts 64 are connected by comparatively heavy cables 95, which are provided with suitable loops 69 to the respective terminals 51 of the crucible heating coil 48. The cables 95 and Et are of such dimensions as to materially reduce the voltage of the current and prevent overheating of the conduits. A suitable switch device or circuit breaker 9 heretofore mentioned is provided with matching contacts for engagement with the contacts 62 and 615 on the bracket 58 in the circuit closing position.

The base 2 has a top 69 in which the bearing 28 at the top is located and through which the shaft 3 extends. On this top 69 are a pair of parallel bars 1I forming a frame for the support of the burn-out muie ll at one end, and a suitable transformer 13 at the other end. These parallel frame bars 1| are fixed. On the top of the bars 1i is a plate 14 with an upright arcuate flange 16. The adjacent whirling or spinning shaft 33 above said flange 19 is hollow and it has in it a piston 11. A coil' spring 'E8 is connected at one end to the piston 11 and at its other end to the inside of the bracket 59 to normally urge the piston 11 toward the end of the said spinning shaft 33. A roller abutment 19 extends downwardly from the piston 11 and through a slot 8| in the lower portion of the shaft 33. This abutment roller 19 rides on the arcuate flange 19 at the initial turning of the spinning mechanism l. When the abutment roller 19 rides off the flange 15 the spring 18 snaps the piston 11 rapidly and draws a suction in a tube 82 which extends from the inner end of the cavity in the shaft 33 to the top of the casing of the casting or wax mold 31. A plug tube 83 is insertable in a hole or chamber 8:1 in the casing 3d which is connected by a passage 89 to the molding cavity 42. The plug tube 83 is on the top of the tube B2 so that the suction drawn by the piston 11 draws the air from the casting cavity d2 at the beginning of the whirling thereby prevents the forming of air pockets and bubbles in the casting.

When the spring l1 is wound up ready for whirling, the roller guide or roller abutment 19 is pulled inwardly of the guide flange 15 so as to cock the piston 11 and be in engagement with the arcuate flange 16. The device is held against whirling by an abutment or catchpin 81. This catchpin 81 is on one of the telescopic bars 89, on which the burn-out mule ll is mounted. The parallel bars 83 telescope into the tubular frame bars 1| and are urged by a spring 89, in the tubular bars 1l, outwardly so as to normally urge and push the sliding bars 38 and the burn-out muflie l l away from the casting mold. In this out of the way position the catchpin 81 is out of the way of the whirling or spinning frame allowing the rotation of the same. At the beginning of the operation, however, and after the whirling or spinning frame is cocked, the burn-out muie l I is pushed in so that the sliding bars 88 slide into the tubular bar 1l and the burn-out mule Il surrounds the casting mold 6. When the burn-out muiile I l is pushed over the casting mold S, a

catch tooth 9| thereon engages a pawl 92 whichI latter is pivoted on the base wall i9 and is ccnnected to the solenoid core 93 of the solenoid I4. I

A spring Bil normally urges the pawl 92 upwardly and holds the same in engagement with the tooth 9i when the burn-out muiiie l l surrounds the casting mold E. Thus the entire device is held assembled in a heating position untilthe solenoid I4 is operated to draw the core 93 thereof downwardly against the action of the spring 94 and thereby to pull the pawl 92 away from the tooth 9| and allow the springs 8,8 to push the sliding shafts Si! and the burnfout inutile i! outwardly and away from the casting meldt, thereby disengaging the catchpin Si? from the whirling frame 4 and allowing the spinning of the entire spinning mechanism.

The electric connections for the operation of the devices in the whirling part of the inscha-V nism are accomplished through the circuit break er 9. This circuit breaker 9 includes an arm 9E pivoted on a bese plate 9'! so as to be swingable toward and away from the bracket 53 at the adjacent enel of thes pinning shaft 33,. On this pivoted arm 95 are a set of terminal contacts, ar. ranged in pairs symmetrically with the pairs of terminal contacts 62 and 64 on the braclrety 56. These terminal contacts 5'.' and 93 respectively contact the4 opposite terminals or contacts 552. and 6d on the bracket 58 when the. arm S5 is in oircuit. closing position. The terminal contacts 91 and 93 are connected into electric circuit. and

release particularly shown in the wiring diagram.

in Fig. 'l'. A suitable mechanism t@ is pivoted on an overhead bracket 98 supported onthe top 59, of the central base 2, and is pivot-ally connected to the top of the core of the solenoid. I6, so as to. normally hold the circuit breaker 9. in a closed position and to release it at the, predeterminedv operation of theselenoid it.

Thus in the general operation of the device.

when the spinning or whirling frame i is cocked and held in position by the catchpin t?, and the burn-out niufleil is around thecasting mold E,

the suitably controlled electric circuits keep theV burn-out rnue il at a temperature for melting out, the wax in the wax inold 37., After a predetermined suitable period, after the gold 5?., or

other metal used melted,y it iows downwardly on the crucible bottom and flows over to bridge the gap between the terminals it and iii. By suitable delayed ction r hereinafter described, ater a predetermined period subsequent to said bridging, the circuits of the solenoids ill and i6 are closed and the pawl 522 is pulled out to release the catch tooth 9i and the link mech anisin il@ is operated to move the circuit breaker 9 away from the bracket 5e thus the spinning trarne i is free begins it" whirling motion under action of the flat spring ii. as the roller abutment 7S the guide flange l5 it snaps outwardly and the piston suchs-thefair from the cavities of the wasy mold t?! and. conf tinued whirling forces holte gold or metal, by centrifugal force, into the mold cavities 42. When the spring il is. completely unwound the traine tstops. and the mold E can he removed and the casting out in the manner.

The preferable circuit for the operation and control of the various devices is shown in the wir--v ing in The lini; depending from the. saine. An arcuate link i533 xtends from the lower end or the. rrst link` |02 andy has its end slidable on e, Eiid extended from the circuit breaker arm 95. A spring iti.

on the pin itil maintains the inni: it under ten sion. Another link is formed ci twoiyoted sections it? and the pivote connection between the links l'and it and the other section itt is pivoted to the top of. the core iof the solenoid i6. Asettingbar `As soon4 chanismm et includes a link M52V pivoted on the outer end ci the bracket $8 and.

The section itil pivote-d tov isfastened tol the. pivot of the eccentriclink |52A whereby the lnl: |32 canbeturned ina clockwise direction viewing Fiel., 1 for pulling the link 93 and turning thelever arm 9,6 to a circuit closing position, At thesaine timev the pivoted linlrs I 07 and it are pulled. upwardly and the solenoid core. H19 is pulled up. Whenthe solenoid it, is energizcd, it pulls the core 239' downwardly which pulls down the pivoted links i'i and Hi8 and thereby swings the link. |01 downwardly and in contracloclmvise direction, land the linl. |33 and lever arm :lt to the circuitopening position shown inliig. l.

The operation ci the device is controlled by an electric circuit illustrated on the wiring diagram in '7. A timer switch 2 is interconnected between the lines ii@ and H4 leading 'to the contact or circuit cracheu terminals Siv which confect to 'the contacts E2 leading to the heating element 4d of the crucibie "i, The timer tit is of such construction that it can be set to pre-F determined period within which to close the circuit therethrough, IThe line H3 is connect-cd to a suitable supply line H5. The other line it is connected toan outlet terminal of niuile actuated normally resiliently open switch i Sil. One end of the heatirgl coil i i@ of the burn-out munie is conncctedl to the source of supply through line |13, and the other end ot the inutile heating coil liti. connected to the' outlet terminal of said' inuleactuated switch i6. The intalte terminal ci reunie actuated switch HS connected by a line lil to the other lineA H8 of said source ci elecicity. The burn-out Inutile has a circuit closing abutment l I9 which abuts and closes the switch H6; Said switch HS is suitably fastened on the base so as to be abutted by said tinent lill when the inuie is pushed over the inclo.

The Contact @2 leading from the spaced points it and 5| connect through the other contacts of the circuit breaker 9 to a delayed relay iili. One of the terminals 9'5 is connected by a line .23 toons of the main lines H53-,` the other 5erminal 92 is connected by a wire |23 to an through the solenoid relaycoil |2| and then another solenoid lineY |24 to the other main line H51 Thus whenever the gap between the terminals Iii? and iii inthe Crucible is closed by the melted metal, the relay i2! is energized and ait-er suitable delay, it closes a switch |23 to the cir-- cuits of the solenoids i4 and 6; Lines or wires |21 lead from the solenoids |4 and I to a wire |25 which latter connects to the main current supply line iid. And theintake lines itl leading to the solenoids ii and i6 are connected with the outlet terminal of the relay switch |252 and through that switch i and the line ili to the other main line H5.

In operation the castingcavities are `:formed in the usual manner in the wax mold 3l and casing 5S is mounted upon the whirline` arni or shaft and against'the insulating plate 3B. Then the suction linee is connected into the casting device. The gold Ell or other suitablev metal is inserted and placed. upon the bottom ofv the Crucible; chamber' 4l'. Then the whirling 4 is'rotated to cock the atspring il. lll/aile the frame Il' is held manually in the cocked posi.- tion the burn-out niul'ee H is pulledl over the casting device t until the tooth 9| thereoi on the pawl 92 and thus the. burn-out munie is heldin position, andthe abutment H9 closes the muie actuated switch HB. In this manner the stop pin 81 arrests the whirling frame 4 and holds it against rotation. The crank bar i I i is turned to close the circuit breaker S, as heretofore described. The timer H2 is now set to the period estimated for the burning out of the wax in the mold B and finally a main supply switch 32 interconnected in the supply line H8, is closed. The current is immediately connected to the wires l I3 and l ill and to usual heating coil of the burnout muiiie il. After the burn-out muiiie il operates for the predetermined period, the timer H2 closes the electric current through the lines H3 and lill and through the closed circuit breaker S. Thus the circuit is automatically closed after the predetermined time through the closed circuit breaker il and to the'heating coil [i8 of the crucible 1 which heats and melts the metal 52. When the metal 52 melts it flows down on the inclined bottom 53 of the crucible and bridges the gap between the terminals llil and El, thus closes the circuit to the delayed relay IZi, which latter after a certain delay to allow all the metal 52 to melt, operates to close the switch 126 thereby to close the circuit of the solenoids IG and H5 through the lines i3i. The energized solenoids Hl and i6 respectively pull down the pawl 92 and pull down the circuit breaker link mechanism 99 to push out the Circuit breaker lever 95 so as to respectively and simultaneously release the burn-out muflie il and disconnect the circuit breaker 9. The springs 89 push the burn-out mufe l l into an out-of-theway position and thus move the catch pin 8l out of the Way of the spinning frame il, and simultaneously open the muiiie actuated switch H9. Thus released the whirling mechanism under the action of the flat spring il is whirled about at a suitable speed. At the beginning of its rotation, as soon as the roller I9 rides off and clears the arcuate iiange 16, the piston l'i in the shaft 33 is snapped by its spring i8 so as to draw air out through the suction tube 83 and from the cav ities of the wax mold 31. The centrifugal force of rotation expels the molten metal 52 through the Crucible mouth 44 into the cavities 42 of the wax mold 3l and finally stops. It is to be noted that by the time the device stops all the electric circuits are open and disconnected.

The device, after it is set, performs all the operations automatically without any need for watching the operation of the machine at any time. The machine can be left in the laboratory by itself and performs the cycle of operations required for centrifugal casting so that any danger or damage is positively avoided. The parts of the device can be easily removed and replaced as needed.

I claim:

1. In a centrifugal casting device, the combination with a crucible, a mold adjacent the crucible, and a rotating device to rotate said crucible and said mold together as a unit for eX- pelling molten material from said crucible into said mold, an electrical heating circuit for said crucible, said crucible having therein the terminals of a releasing electrical circuit adapted to be closed by the molten material in said crucible; of a burn-out muiiie removably extending around said mold; a releasable device to arrest the rotation of said rotating device, electrically actuated means to release said releasable device, an electrical circuit for said electrically actuated means in series with said terminals, an electrical heating circuit for said muiile, and a timer switch connected in parallel with said muiile heating circuit and in series with said crucible heating circuit to regulate the closing of said crucible heating circuit relatively to the closing of said muiiie heating circuit.

2. In a centrifugal casting device, the combination with a Crucible, a mold adjacent the crucible, and a rotating device to rotate said crucible and said mold together as a unit for eX- pelling molten material from said crucible into said mold, an electrical heating circuit for said crucible, said crucible having therein the terminals of a releasing electrical circuit adapted to be closed by the molten material in said crucible; of a burn-out muiile removably extending around said mold; a releasable device to arrest the rotation of said rotating device, electrically actuated means to release said releasable device, an electrical circuit for said electrically actuated means in series with said terminals, an electrical heating circuit for said muiiie, and a timer switch connected in parallel with said mule heating circuit and in series with said crucible heating circuit to regulate the closing of said crucible heating circuit relatively to the closing of said muiiie heating circuit, and releasable means to simultaneously connect said muiiie heating circuit and said time switch to an electric supply circuit.

3. In a centrifugal casting device, the combination with a crucible. a mold adiacent the crucible, a rotating device to rotate said crucible and said mold together as a unit for expelling molten material from said crucible into said mold, an electrical heating circuit for said crucible, said crucible having therein the terminals of a releasing electrical circuit adapted to be closed by the molten material in said crucible; of a burnout mufile removably extending around said mold; a releasable device to arrest the rotation of said rotating device, electrically actuated means to release said releasable device, an electrical circuit for said electrically actuated means in series with said terminals, an electrical heating circuit for said muffle, and. a timer switch connected in parallel with said muiiie heating circuit and in series with said crucible heating circuit to regulate the closing of said crucible heating circuit relatively to the closing of said muiiie heating circuit, and releasable means to simultaneously connect said muiiie heating circuit and said time switch to an electric supply circuit, and means actuated simultaneously with the operation of said releasable device to release said releasable means for disconnecting said electric supply circuit vfhen said releasable device is released.

4. In a centrifugal casting device the combination with a whirling mechanism, a frame rotated by said whirling mechanism, a mold on the frame having a molding cavity therein, a crucible between the axis of rotation of the frame and said mold and being connected by a passage to said cavity to transfer molten material, from the crucible into said cavity by centrifugal force as said crucible and mold are rotated together with said frame; of a burn-out inuiile movable over said mold to burn out wax filling from said Cavity, a non-rotatable support for said mufile being slidable relatively to said frame for moving said mrfile over and olf said mold, means to normally urge said support in a direction to remove said mriile off said mold, a releasable catch device to hold said muiiie over said mold, and a device movable with said muiiie to prevent rotation of said frame when said mule is over said mold and to release said frame when said catch device is released and said muilie is removed from said mold.

5. In a centrifugal casting device the combination with a whirling mechanism, a frame rotated by said whirling mechanism, a mold on the frame having a molding cavity therein, a crucible between the axis of rotation of the frame and said mold and being connected by a p-assage to said cavity to transfer molten material from the crucible into said cavity by centrifugal force as said crucible and mold are rotated together with said frame; of a burn-out muiile movable over said mold to burn out wax filling from said cavity, al catch device to hold said muiiie over said mold,

an element associated with said muiile to prevent the rotation of said frame while said muie is over said mold, and means actuated by said catch device to remove said muiile from said mold when said catch device is released.

6. In a centrifugal casting device the combination with a whirling mechanism, a frame rotated by said whirling mechanism, a mold on the frame having a molding cavity therein, a Crucible between the axis of rotation of the frame and said mold and being connected by a passage to said cavity to transfer molten material from the crucible into said cavity by centrifugal force as said crucible and mold are rotated together with saidl frame, said whirling mechanism including a stationary base, a device in the base supporting said frame and imparting rotation to said frame, of a pair of guides on said base below said frame and being generally parallel with said frame, a burn-out muiiie movable over said mold to burn out wax from said cavity, supports for said burnout muiile reciprocable in said guides alternately to carry said muflie over said mold and away from said mold, spring elements for normally urging said supports and said muflie away from said mold, an element associated with said support and engaging said frame when said muie is carried over said mold to arrest the rotation of said frame and releasing said frame when said muilie is removed from said mold, a catch device connected to said muille to hold said muilie on said mold, and releasing means for said catch device.

7. In a centrifugal casting device the combination with a whirling mechanism, a frame rotated by said whirling mechanism, a mold on the frame having a molding cavity therein, a crucible between the axis of rotation of the frame and said mold and being connected by a passage to said cavity to transfer molten material from the crucible into said cavity by centrifugal force as said crucible and mold are rotated together with said frame, a releasable catch device to arrest the action of said whirling mechanism on said frame, an electric releasing device to release said catch device, a normally open electrical circuit to actuate said releasing device when said circuit is closed, said circuit being open by a gap within said crucible, said material being electrically conductive and flowing over and bridging said gap when melted for closing said electrical circuit for releasing said catch and permitting the rotating of said frame by said whirling mechanism, of an electrically heated burn-out mufe movable over said mold to burn out wax from said cavity, an electric circuit for heating said Crucible, a normally open time switch interconnected in said heating circuit to close said Crucible heating circuit after a predetermined period, said time switch and the electric heating circuit of said muie being connected in parallel to a source of electricity, a normally open switch in series with said time switch and said mufle heating circuit, and means associated with said muiiie to hold closed said last mentioned normally open switch when said muiiie is moved over said mold.

8. In a centrifugal casting device the combination with a whirling mechanism, a frame rotated by said whirling mechanism, a mold on the frame having a molding cavity therein, a crucible between the axis of rotation of the frame and said mold and being connected by a passage to said cavity to transfer molten material from the Crucible into said cavity by centrifugal force as said Crucible and mold are rotated together with said frame, a releasable catch device to arrest the action of said whirling mechanism on said frame, an electric releasing device to release said catch device, a normally open electrical circuit to actuate said releasing device when said circuit is closed, said circuit being open by a gap within said Crucible, said material being electrically conductive and flowing over and bridging said gap when melted for closing said electrical circuit for releasing said catch and permitting the rotating of said frame by said whirling mechanism, of an electrically heated burn-out muiiie movable over said mold to burn out waX from said cavity, an electric circuit for heating said crucible, a normally open time switch interconnected in said crucible heating circuit to close said Crucible heating circuit after a predetermined period, a normally open switch connected in series between said time switch and a source of electricity, means associated with said muffle to hold said last normally open switch closed when said. muille is moved over said mold to cause said time switch to determine the interval between the muiile operation over said mold and the heating of said crucible.

ADOLPH J. KEMPPE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,113,333 Hansen Oct. 13, 1914 1,158,972 Boeck Nov. 2, 1915 1,310,865 Hollenback July 22, 1919 1,493,692 MiXOn May 13, 1924 1,498,562 Maupin June 24, 1924 1,657,063 Brown Jan. 24, 1928 1,767,023 Thomas et al June 24, 1930 1,802,892 Hansen Apr. 28, 1931 1,962,705 Brown June 12, 1934 2,004,457 Beringer June 11, 1935 2,257,475 Metz Sept. 30, 1941 2,265,043 Moore Dec. 2, 1941 2,338,560 Yaruss Jan. 4, 1944 2,363,759 Waldie Nov. 28, 1944 2,479,610 Frei Aug. 23, 1949 2,509,670 Capita et al May 30, 1950

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