US2529291A - Apparatus for applying mold wash - Google Patents

Description

Nov. 7, 1950 T. K. GRAHAM APPARATUS FOR APPLYING MOLD WASH Filed Dec. 17. 1948 FIG.I

FIG.3

FIG. 2

INVENTOR Tfiawas 15f Grafiem BY 11 g luJM yfiw ATTORNEY Patented Nov. 7, 1950 APPARATUS FOR APPLYING MOLD WASH Thomas K. Graham, Great Falls, Mont., assignor to Anaconda Copper Mining Company, New York, N. Y., a corporation of Montana Application December 17, 1948, SerialNo. 65,763

This invention relates to apparatus for applying mold wash to molds, and for like purposes. In thecasting of molten metal in metallic molds it is customary to coat the mold' with an aqueous suspension of finely divided bone ash, finely divided alumina, or other refractory material. Such a suspension is called mold wash. It serves to improve the quality of the casting, especially its surface, and to prevent sticking of the casting to the mold. Heretoiore it has usually been applied by swabbing or painting it on the mold surface shortly before casting the molten metal.

The apparatusof the" invention is effective for applying mold wash to molds automatically. It is designed to insureeven and complete coating of the mold; It is especially adapted to apply mold wash automatically to permanent metallic molds mounted at intervals about the periphery of a casting wheel-such-as is used in casting cop'- per anodes, wirebar's, etc. When used in connection' with such molds-it reduces to aminimum the manual labor incident to applying-the mold washg-and'thereby its use leads to important operating economies:

The new apparatus comprises a pivotally mounted pneumatic spraynozzle to which is connected a source of moldwash. A spring is arranged for urging the-nozzle to one limit of its pivotal mounting, in which position it is normally held; and apneumatic cylinder having a piston connected to the nozzle is provided for moving the nozzle on its pivotal mounting through an are against the force of the spring to direct it from one end tothe other of the mold. Asource of compressed air is connected through a normally closed, electrically opened controlvalve (e. g. a solenoid valve) both to the air cylinder and to the nozzle. An electrical relay connected to the valve opening means and to a power source serves when energized to effect opening of the. control valve. Thereby compressed air is admitted to the nozzle for spraying air enters thepneumatic cylinder so that the rate at which the nozzle is-mOVed through its arcuate path may be adjustedin relation to'the pressure of the compressed air. A timer is connected to the relay for de-energizing it, and through it for lie-energizingthe valve opening means, upon 6 Claims. 01. 22'88) 2 I elapseof a predetermined time interval following initial energization of the relay. Thereby,at the end'of such time: interval, the control valv'e is closed, the flow of mold wash from the nozzle is discontinued; andthe nozzle isreturned'by'the spring to its original position. V p a A presently preferred embodiment of themvention, incorporating the foregoing and other features, is shown in the accompanying drawings, in which -F'ig'. 1 is aplan of the new apparatusposi tioned at the periphery of an anode casting wheel;

Fig. 2 is an elevation of the apparatus shown in Fig; 1-; and" Fig. :3 is a diagram of one form of electrical control circuit for automatic operation of "t apparatus. v ,I

The new apparatus It! for applyingmold wash is shown in Figs; 1' and 2 positioned near the periphery of a castingwheel'l'l carrying a series of anode (or other) molds l2, it, etc., at spaced angular intervals. At various stations around the periphery of the casting wheel a coating a: mold wash is applied'to'an empty mold l'2,'molten copper is. cast into a previously coated mold, hot cast anodesinmolds are cooled with water sprays, and solidified anodes "are'removed from the molds.

.Periodically, as these operations are completed at each station, the casting wheel is rotated through theangular distance between molds to bring a new mold to each station and'the op erationsare repeated; This conventional opera tion of the casting wheel is not itself a part of the invention, but the operation'of the apparatus It for applying the-mold wash, which does con; stitute' the subject matter of the invention, is correlated with operation" of the casting'whee'l so as to apply a coating'of mold wash'to each mold as it comes" into the position occupied by the mold |2 in Fig 1. '1.

The" apparatus Hi comprises a tank [4 sup ported'on legs and'kept filled to a constant level witlr'a' supply of mold wash delivered from a reservoir or mixing tank through a pipe l5 and a float-controlled valve 16'. A light framework] ll advantageously made of pipes and pipe fittings extends upwardly from thetank' It and supports a series of pneumatic nozzles It by which mold wash is sprayed into the cavity of the anode moldi2 in position for receiving mold washj Thenozzlesare mounted in a row on a supporting bar 19 which is free to turn on its axis through at least'a small-arc. A'Iever 26 is also secured, to this supportbarter-rotating it and the nozzles mounted on it through the arc of travel, so that a stream of mold wash 2| being discharged from the nozzle may be directed from one end to the other of the mold, thereby to coat the entire mold cavity.

A pneumatic cylinder 22 mounted for tilting movement on a pivot support 23 carried by the framework contains a -piston24. A connecting rod 25 connects the piston with the lever 20 by which the nozzle support bar is turned. A compression Spring 26 bearing against the end of the cylinder 22 and against the lever 28 urges the support bar into the position shown in Fig. 2 for directin the spray of mold wash into the end of the mold cavity that is nearest the spray apparatus. When, however, compressed air is admitted to the cylinder, the piston is forced to the rear of the cylinder and pulls the lever 28 back against the pressure of the spring 26, thereby tilting the nozzles in a clockwise direction (as viewed in Fig. 2) to direct the stream of mold wash alon the length of the mold to the end of thecavity that is remote from the spray apparatus.

.7 Compressed air is supplied to the cylinder 22 for the'above purpose from a header pipe 2! through a flexible branch hose 28 and an adjustable needle valve 29. The needle valve permits adjustment of the rate at which the piston 24 is forced to the rear of the cylinder 22 in relation to the pressure of compressed air in the header 21, and thereby permits control of the time of travel of the mold wash spray from one end to the other of the mold cavity.

The position at which the connecting rod 25 is pivotally fastened to the lever 28 is made adjustable so that the magnitude of the arc. through which the nozzles are tilted by the pneumatic cylinder may be adjusted to conform with the length of the mold. The mounting of the cylinder 22 on the pivot support 23 permits this adjustment to be made, and permits back and forth movement of the piston 24, even though the connecting rod be rigidly connected to the piston.

A series of flexible branch hoses 38 are provided to connect each nozzle l8 with the compressed air header pipe 21. Each nozzle is also connected to the constant level tank by a flexible hose 3| through whichmold wash is delivered to ply' pipe 34. Also connected series with this pipe is a solenoid-operatedmain control valve 38 for turning on and off thesupply of air to the header pipe 21' durin normal operation of the apparatus, The solenoid valve is normally closed, and normally there is no discharge of mold wash from the nozzles and the nozzle support bar is tilted by the spring to the limit of its travel shown in Fig. 2. When the solenoid valve 38 is opened, however, and compressed air is thereby admitted to the header pipe, some of the air flows to the nozzles l8 and causes the spray 2| of mold wash to be discharged therefrom, and

some of the air flows into the pneumatic cylinder 22 and causes the nozzles to be tilted in the manner described above. When the solenoid valve is again closed, the flow of compressed air through the pneumatic nozzles I8 is cut ofi and the spray of mold wash stops. Thereupon the cylinder 22 is vented to the atmosphere through the header pipe and the nozzles, permitting the spring to return the piston and the nozzle support bar to their original positions.

To facilitate venting the air cylinder 22, and also to permit finer adjustment to be made by the needle valve 29 in the rate of travel of the piston 24 to the rear of the cylinder when compressed air is admitted to the header pipe, a very small hole 39 is drilled in the cylinder wall near the needle valve. The hole is made small enough so that the flow of compressed air into the cylinder through the needle valve when the control valve 38 is opened is faster than its escape from the cylinder to the atmosphere through this hole.

In order to provide for automatic operation of the apparatus, the solenoid 40 which when energized opens the main control valve 38 is connected in circuit with a relay. 4|, a timer 42, a normally opened switch 43, and a power line 44. The. arrangement is such that when the switch 43 is closed momentarily, the relay 4| closes, thereby energizing the solenoid and opening the valve 38. At the same time the timer 42 is set in operation, and after a predetermined time interval, it effects reopening of the relay 4|, thus deenergizing the solenoid and causing the valve 38 to close again. The time interval provided by the timer 42 for keeping the valve 38 open is made just sulficient for spraying the interior of the mold cavity uniformly from one end to the other witha coat of mold wash. i l

' The switch 43, which is of the type that is normally held open by a spring, is mounted near the periphery of the casting wheel II. It is provided with a lever 45 by which it may be momentarily closed, andthis lever is-located so as to be en-. gaged by any of a series of switch-tripper lugs 46 mounted about the periphery of the wheel. These. switch-tripper lugsare spaced apart by angular intervals equal to thespacing of the molds. The position of the switchand 'of the lugs 46 on the castin wheel is such that the switch 43 is momentarily closed each time a mold |2 comes into position to receive a coat of mold wash, and upon such closure of'the switch 43, the mold, wash applying apparatus I8 is set into operation in the manner described.

An advantageous electrical control circuit including the relay 4|, the timer 42, and the switch 43 is shown diagrammatically in Fig. 3. The relay 4| includes a solenoid 41 which ,operates two normally opened contacts 48 and 49 and a normally closed contact 58. The valve solenoid winding 5| is connected to the, power-line: 44 through one of the normally opened contacts 49; One terminal of the relay solenoid 41 is connected to one side of the power line 44 througha parallel circuit one leg ofwhich includes the switch 43 and the other leg .ofwhich includes the other normally opened relaycontact 48. The. other terminal of the relay solenoid is connected to the other side of the power supply line through a timer relay contact 52 which is'held closed so long as a timer solenoid 53 is energized. This timer solenoid is supplied-with direct curenergized from .the power transformer 55.

Operation of the control circuit is as follows The circuit is shown in Fig.3 in the position in whichv the solenoid coil .5 I. is de'energ-ized. and: in which therefore the valve 33. 'is:closed.' When the casting wheel ll rotates enough tobring a new mold into position to receive a coat of mold wash, the switch 43 is momentarily closed by one of the switch-tripper lugs 48. Thereby a circuit connecting the relay solenoid 41 t the power supply line 44 is completed through the switch 43 and through thetimer contact 52. In consequence the normally opened relay contacts 48 and 49 are closed, and the normally closedrelay contact 59 is opened. This at once completes a circuit from the power line throu'ghtherelay contact 49 and valve solenoid. winding: 5i and ca-usesthe valve 38 to'open; At-the same time the circuit through the relay solenoid. 4? isclosed. through the relay contact 48;so that-"if now the switch 43 is'reopened, the relay solenoid is not on that account de-energized. The circuit through the timer solenoidiit -is broken as a result of opening the normally closed rclaycontact 58, but the timer'relay contact dt'does not openat once because when the magnetic 'field' 'in the timer solenoid 53 begins to'd'ecay; a current tending to oppose such decay-is generated-in it copper ring 56 surrounding the solenoid. The effect- 0f this ring is to delay the decay of the magnetic field in the timer solenoid'for an appreciable-period of time. After'a lapse' of some time interval, however, it does decay to the point at which the timer contact 52 opens, and when this ccurs, the relay fill is at once de-energized. Thereupon the circuit through the valve solenoid winding 5| is broken and the valve closes. Simultaneously the circuit through the timer solenoid is closed again through the normally closed relay contact 56, once again causing the timer contact 52 to close; but now the relay solenoid fl'l remains de-energized because both the switch 43 and the normall pened relay holding contact 48 areboth open. Thus the circuit is once more in the position to go through the'same cycle of operations.

I't' is evident that the length oi time for which the valve 38 is held open is determined by the time required for decay of. the'magnetic field in the timer solenoid 53. This may be controlled by increasing or decreasing the number or size of the copper rings 56. In lieu of the copper rings, the timer solenoid may include a separate timer winding in which the current opposing decay of the magnetic field is induced. The rate at which this current is allowed to dissipate, and hence the timing cycle of the timer, may be controlled by short-circuiting such timer winding through an adjustable high resistance potentiometer or rehostat.

The particular construction of the timer and relay is not a part of the present invention. A suitable form of timer and relay has been described solel for the purpose or providing a full disclosure of a complete operative apparatus. There are many different types of relays and many different types of timers, including mechanical timers and electronic timers in addition to electromagnetic timers such as that described above, available on the market and any of them may be adapted for use in the apparatus of the invention.

I claim:

1. Apparatus for automatically applying mold wash to a mold compromising a pivotally mounted pneumatic spray nozzle, a source of mold wash connected to said nozzle, means for moving the nozzle about its pivotal mounting to direct it from one end to the other of the mold comprising a pneumatic cylinder having therein a piston connected to the spraynozzle, spring means urging the nozzle to one limit of its pivotal movement, a source of compressed air connected through a valve to said cylinder and also to said nozzle, electrical means for opening said'valve; an electrical relay connected to said valve open ing means and serving when energized to encr gize said valve opening means, whereby com pressed air'i's admitted to the nozzle for spraying mold wash therefrom and simultaneously to the pneumatic cylinder for moving thenozzleto the other limit ofitspivotal movement to direct the mold wash over the length of the moldyand a timer connected to said relay for de-energizing the valve opening means upon elapseof a pre-' determined time interval following 'the energization of the relay, whereby iter said time interval the valve is closed, the newer nold'wa'sli from the nozzles is discontinueifand the, spray nozzle'is returned by the springiinean's toflits original position. j 2, The combination-with a casting; wheel my; ingv a. pluralityoi molds mounted about its p e riphery and wheel-rotating means for per iodi-.

cally indexing the wheel angularly through the distance between twomolds, of apparatus for automatically applying mold wash to .a'gmold each time the wheel is indexed comprisingaa,

spray nozzle mounted ior pivotal movement ad:

connected to the nozzle, a source of compressed air connected through a solenoid-opcrated valve to said cylinder and also to saidnozzle', an elec trical relay connected in circuit with the "valve" solenoid, a switch mounted adjacentthe peripn f ery of the casting wheel and connected'incircuit with said relay and a power source, a tripper for said switch mounted on the casting-wheel in such position as to actuate the switch each time the wheel is indexed, thereby to energize the valve solenoid and admit compressed air to the nozzles for spraying mold wash therefrom and to the air cylinder for moving the nozzle on its pivotal mounting, and a timer connected to said relay for de-energizing the valve solenoid after elapse of a predetermined time interval, whereby upon such lapse of time the valve is closed, the flow of mold wash from the nozzles is discontinued, and the'spray nozzle is returned by the spring means to its original position.

3. In apparatus of the character described, a pneumatic spray nozzle pivotally mounted for travel through an arc, spring means urging the nozzle to one limit of its travel, a pneumatic cylinder having therein a piston connected to said spray nozzle for moving it against the spring means to the other limit of its travel, an air supply header pipe connected both to the air cylinder and to the nozzle, a source of compressed air connected to the header through a normally closed valve, electrical means for opening said valve, a relay connected to said valveopening means and to a source of electrical power, a switch connected to the relay for actuating it to energize the valve-opening means, and a timer connected to the relay for de-ener- 7 gizing it after elapse of a predetermined time interval.

4. In apparatus of the character described, a pneumatic spray nozzle pivotally mounted for travel through an arc, spring means urging the nozzle to one limit of its travel, a pneumatic cylinder having therein a piston connected to said nozzle for moving it against the spring means to the other limit of its travel, an air supply header pipe connected both to the air cylinder and to the nozzle, a source of compressed air connected to the header through a normally closed valve, whereby when the valve is opened compressed air is admitted directly to the nozzle and also to the air cylinder to move the nozzle against the spring means through its arc of travel, and an adjustable needle valve connected between the header pipe and the pneumatic cylinder, whereby the rate of travel of the nozzle through it path of travel may be adjusted in relation to the pressure of the compressed air from the source.

5. lin apparatus for applying mold wash to a mold, a nozzle support bar mounted for pivotal movement through an arc, a series of nozzles mounted on said support bar, a source of mold wash connected to each of said nozzles, a spring urging the support bar to one limit of its arcuate travel, a penumatic cylinder having therein a piston connected to said support bar for moving it against the spring to the other limit of its arcuate travel, a compressed air supply pipe connected directly to each nozzle and through an adjustable needle valve to the air cylinder, and a source of compressed air connected through a normally closed control valve to said supply pipe, whereby when saidcontrol valve is opened compressed air is admitted to the nozzles to cause a spray of mold wash to be discharged therefrom and to the air cylinder to cause the nozzle support bar to move through its arcuate path of travel at a rate determined by the setting of the needle valve, and whereby when the control valve is closed the discharge of mold wash from the nozzles is discontinued and the nozzle support bar is returned by the spring to its original position.

6. In apparatus for applying mold wash to a 8 mold,- a nozzle support bar mounted for pivotal movement through an are, a series of nozzles mounted on said support bar, a source of mold wash connected to each of said nozzles, a spring urging the support bar to one limit of its arcuate travel, a pneumatic cylinder having therein a piston connected to said support bar for moving it against the spring to the other limit of its arcuate travel, a compressed air supply pipe connected directly to each nozzle and through an adjustable needle valve to the air cylinder, a source of compressed air connected through a normally closed solenoid control valve to said air supply pipe, a normally opened relay connected to apower source and to the valve solenoid, means for, closing the relay to energize the solenoid and thereby open the control valve, and a timer connected I to the relay for reopening it upon elapse of a predetermined time interval after it has been closed, whereby when the relay is closed the control valve is opened and compressed air thereby admitted to the nozzles causes a spray of mold wash to be discharged therefrom and compressed air simultaneously admitted tothe air cylinder causes the nozzle support bar to move through its arcuate path of travel, and whereby after a predetermined time interval the relay is opened and there by the solenoid valve is closed causing the flow of mold wash from the nozzles to be discontinued and enabling the spring to return the nozzle support bar to its original position.

THOMAS K. GRAHAM.

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

UNITED STATES PATENTS Mero Nov. 9, 1948,

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