US3554522A

US3554522A - Controlled tiling apparatus for metallurigical furnace

Info

Publication number: US3554522A
Application number: US829427A
Authority: US
Inventors: Henry O Herrmann
Original assignee: Pennwalt Corp
Current assignee: Pennwalt Corp
Priority date: 1969-06-02
Filing date: 1969-06-02
Publication date: 1971-01-12
Anticipated expiration: 1988-01-12

Abstract

Apparatus for tilting a metallurgical furnace at duplicatable predetermined speeds including ''''slow,'''' ''''quick'''' and ''''throw'''' tilting rates. Forward and backward tilting of the furnace can be performed manually, semiautomatically or automatically by selective actuation of solenoid-operated hydraulic control valves. The furnace may be rocked between a predetermined back tilted position and a front prepouring position, and safety interlocks are provided to prevent electrohydraulic actuation in manual position or manual tilting when in semiautomatic or automatic positions.

Description

I United States Patent 1111 3,55 ,5

[72] Inventor Henry 0. Herrmann [56] References Cited gggz gp UNITED STATES PATENTS PP 1,888,317 11/1932 Hind m1. 266/36 1 FM M11969 2,999,482 9/1961 Bower 91/6 [451 Famed Jan-12,1971 3,038,449 6/1962 Murphy m1. 91/6 [731 AS51811 l 3,201,106, 8/1965 Lafay 266/36 phlladelpl'ja 3,207,002 ,9/1965 Lakin m1 266/36 a corporation of Pennsylvania Primary Examiner-Gerald A. Dost Attorneys-Carl A. Hechmer, Jr. and Stanley Bilker ABSTRACT: Apparatus for tilting a metallurgical furnace at duplicatable predetermined speeds including slow, quick [54] #:ggKg FOR and throw" tilting rates. Forward and backward tilting of the m cm 6 Drawin Fi furnace can be performed manually, semiautomatically or au- 3 tomatically by selective actuation of solenoid-operated [521 US. Cl 266/36, hydraulic control valves. The furnace may be rocked between 9l/6, 91/3], 91/411, 91/427 a predetermined back tilted position and a front prepouring [51] Int. Cl F27d 19/00 position, and safety interlocks are provided to prevent elec- [50] Field of Search 266/34, 35, trohydraulic actuation in manual position or manual tilting when in semiautomatic or automatic positions.

PATENT-ED JAN 1 212m $554,522

sum 2 OF 3 IN VE N 7' 0/? HENRY 0. HERRMA NN ATTORNEY 1 CONTROLLED TILT ING APPARATUS FOR METALLURIGICAL FURNACE This invention relates to metallurgical furnaces, and more particularly relates to means for controlling the tilting of such furnaces at predetennined speeds which are duplicating during successive runs.

Modern day alloys require great precision in refining and casting techniques in order to reproduce identical high quality grain structures in successive batches. Speed has been of the essence during the pouring of the molten metal from the furnace or crucible into the molds in order to prevent cooling of the metal beyond certain prescribed temperature limits. Also, the rate at which the metal is poured into the molds must be consistent from run to run to insure uniformity of each mold.

in the past, the tilting of metallurgical furnaces or crucibles has been accomplished by manually operated mechanical systems or hydraulic systems under the control of manually operated, mechanically actuated valves. Because manual operation suffers from the inherent human defect of inability to repeat precisely the timing of successive events, the prior furnace pouring systems were deficient in the criticality required of their performance.

It is therefore an object of this invention to provide a means for the controlled tilting of metallurgical fumaces at predetermined speeds which are precisely duplicatable from run to run.

Another object of this invention is to provide a controlled tilt furnace apparatus in which the furnace may be repeatedly discharged at slow," quick" or throw tilting rates.

Yet another object of this invention is to provide an electrohydraulic system for tilting a metallurgical furnace in which manual, semiautomatic or fully automatic sequences are selectively available.

Still another object of this invention is to provide an apparatus for tilting a metallurgical fumace in which safety interlocks are provided to prevent manual control of the tilting when the system is in-automatic or semiautomatic positions or to prevent electro hydraulic actuation when in manual position.

Yet still another object of this invention is to provide a controlled tilt metallurgical furnace which is adapted for use in connection with vacuum degassing operations.

A further object of this invention is to provide an automatically operated controlled tilt vacuum furnace in which the cycle of operations is accomplished only upon attainment of temperature and pressure conditions as well as accurate mold positionment.

Other objects of this invention are to provide an improved device of the character described which is easily and economically produced, sturdy in construction, and both highly efficient and effective in operation.

With the above and related objects in view, this invention consists of the details of construction and combination of parts as will be more fully understood from the following detailed description when read in conjunction with the following drawings in which:

FIG. I, is a schematic view of a vacuum metallurgical refining furnace having a controlled tilting mechanism embodying this invention;

FIG. 2, is a front elevational view of the tilting furnace shown in upright position;

FIG. 3 is a sectional view taken along line 3-3 of FIG. 2; FIG. 4 is a sectional view taken along lines 4-4 of FIG. 2: FIG. 5 is a sectional view taken along lines 5-5 of FIG. 3; and

- FIG. 6 is a schematic diagram of the electrical and hydraulic system for actuating the tilting of the furnace.

Referring now in greater detail to the drawings in which similar reference characters refer to similar parts, there is shown a tilting furnace, generally designated as A, mounted within a vacuum chamber B. The furnace A is adapted to pour refined degassed molten metal under vacuum into a mold C delivered into position within the chamber A through an interlock B1. A hydraulically operated, rotary actuated motor or oscillator A1 is coupled to the trunnions of the furnace A, and by high torque reciprocatory angular motion can effect tilting thereof in forward or backward directions. They hydraulic operation of the rotary actuator Al is electrically controlled through appropriate switch actuated, solenoid-operated hydraulic valves whereby the degree of tilt and the rate of speed of the pouring motion is precisely repeated on successive runs. As shown in FIG. 6, the electrical system comprises a selector switch S1 for manually, semiautomatically, or fully automatically conducting the tilting operations. For semiautomatic operations, there is included a pushbutton switch S2 for providing slow tilting of the furnace in a forward direction, a pushbutton switch S3 providing a slow return or backward tilt thereof, and a pushbutton switch S4 for quick tilt of the furnace in a forward direction to permit throwing or tossing" of the molten metal therefrom.

The furnace A itself is conventional, for example, an induction melting crucible with SO-pound capacity. However, it is to be understood that the embodiments shown are purely illustrative since the principles of the instant invention are applicable to any size or type of furnace or ladle. Similarly, the vacuum chamber B is a structure consistent with good engineering practice for housing both the furnace A and the mold C in order to permit refinement and casting of the metal under vacuum conditions. As shown in FIG. 1, the mold C is elevated into pouring position into'the chamber B by means of a pneumatic or hydraulic ram 12. The interlock valve Bl separates the furnace chamber B from a mold chamber (not shown) whereby the molds may be raised into the melt chamber without breaking vacuum. A temperature sensing device 14, such as a thermocouple or optical pyromter, mounted above the crucible A transmits a signal to a suitable indicator-recorder controller 16. The pressure within the melt chamber is determined by a suitable sensing instrument 18 such as a vacuum gage.

Referring now to FIGS. 2, 3, and 4, the crucible A has a pair of outwardly extending

trunnions

20 and 22 which are rotatably supported in

respective pillow blocks

21 and 23. As shown in FIGS. 2, 3 and 4, the trunnions are located transverse to the cylindrical axis of the crucible and slightly trunnions the horizontal center. However, with the present invention, the trunnions may also be incorporated adjacent the pouring lip 24 at the nose of the crucible as shown in FIG. 1, to allow nose tilting which minimizes free fall of molten metal from the crucible to the molds C.

In order to permit electrical leads to pass freely through the trunnion 22 without interference, the drive for pivoting the furnace is offset from the centerline of the trunnions. Sprocket 26 on trunnion 22 is driven by chain 28 coupled to sprocket 30 on shaft 32. Screw 34 permits adjustment of tension in chain 28. Shaft 32 is joumaled in seal housing 36 which passes through the wall of the melt chamber B. See FIG. 5. Grease fitting 38 is used to lubricate the bearing bushing 40 so that the fumace and its lead can be pivoted while maintaining vacuum within the melt chamber B Shaft 32 is connected to main shaft 42 of rotary] actuator Al through a flexible coupling 44. A handwheel 46 mounted on the exterior of the melt chamber B is coupled to the shaft 32 through chain 48.

Sprockets

50 and 52 in engagement with the chain permit manual tilting of the furnace via the handwheel 46.

The rotary actuator Al is best illustrated in FIG. 6. It comprises a pair of

racks

56 and 58 which are in engagement with an intermediate pinion 60. The rack 56 is formed on the lower portion of a piston 62 which is reciprocable in cylinder 64. Rack 58 is formed on the upper edge of a piston 66 slidable in cylinder 68. The rotary actuator Al operates by introducing fluid power to the piston heads which in turn push the respec tive racks over the pinion 60 thus giving the latter rotary motion. The rotary motion is constant in speed and torque.

line 76.

Hydraulic lines

72 and 76 are coupled through common feed line 78. Correspondingly, counterclockvw'se rotation of the pinion 60 effected by delivering hydraulic fluid to the right-hand port 80 of the upper cylinder 64 through hydraulic line 82 whereby the oil is urged peripherally about the pinion 60 into cylinder 68 against .the rear wall of piston 66. It is to be observed that the left-hand port of cylinder 68 is plugged and includes an adjustable stop 84 for limiting movement of the piston 66 in the left-hand direction.

The rotary actuator A1 is symmetrical and includes a shaft 42 a and a coupling 44 a for mounting in either or both directions. A housing A2 on the right-hand end, as shown in FIG. 2, contains rotary cam limit switches for automatically stopping the forward motion of the crucible A at a predetermined prepouring position or rearward motion at an upright or zero position. v

In semiautomatic position, the direction and speed of rota tion of the rotary actuator A1 is controlled by switches S1, S2, S3, 54, S5 and S6 which electrically actuate a series of solenoid operated hydraulic valves. Switch S1 is a manual, semiautomatic electrical, automatic selector switch which. allows the crucible A to be turned by hand through wheel 46- or semiautomatically by means of the electricalpushbutton switches S2 to S6 inclusive or fully automatically by means of a timer T. One of the further purposes of the switch S1 is ties performance of a safety function by its control of the operation and actuation of two-way solenoid valve V1 which is in normally open position. That is, with switch Sl'in manual position, solenoid 86 is not energized and spring 88 urges the spool of valve V1 downwardly as shown in FIG. 6 whereby hydraulic line 90 is in communication with line 92. In this position it can be seen that the hydraulic pressure from line 72 on the left- A hand side of piston 62 is equal to that on the right-hand side and on the back of piston 66. Therefore, it is possible to tilt the furnace A manually by turning the handwheel 46 in either direction. Also, it is to be noted that switch S1 acts as an interlock since with its contacts in open or manual position, neither valve V2 nor valve V3 can be energized.

, With the switch S1 in,serniautomatic electrical or automatic" position, the circuit through solenoid 86 is closed. Therefore, spool V1 is forced upwardly against the opposing bias of spring 88,, and communication between

lines

90 and 92 is blocked off. Accordingly, any pressure on one. piston, 62 for example, created by rotation of the handwheel, 46 in one direction (counterclockwise)- would be opposed by the pressure on the other piston 64 through line 76. As a result, the handwheel 46 becomes locked'with the switch S1 in electrical position.

Valve V2 is a double-solenoid, four-way, directional control valve for low speed forward or backward tilting of the furnace A. The spool of valve V2 has three positions, neutral or deengergized in which the core blocks off communication. from the pump P as well as return; to the tank or sump 96 right throw in which hydraulic inlet line 98 communicates with line 100 and line 102 with the sump 96, and left" throw in which the inlet line 98 feeds line 102 while line 100 returns to the sump 96 by virtue of the crossover disposition of the channels in the spool core. It is to be observed that pump P delivers hydraulic fluid through a needle valve 104 in line 98. The rate of flow through the needle. valve 104 is adjusted for example at 25 cubic inches per minute, such flow rate being adapted to rotate the crucible A through 90 in approximately five seconds.

Closing pushbutton switch S2 which is in series with a normally closed cam limit switch 106,energizes solenoid 108. The cam limit switch 106 is a rotary switchlocated in housing A2 and is set to restrict the forward position of the crucible inapproximately a 20 to 30 prepouring position. The spool of valve V2 moves to the right by energizing solenoid 108 in opposition to the centering bias of springs 110 and 112. Line 98 is now in communication with line 100 whereby fluid flows intoport 80 through line 82. Piston 66 moves to the right causing the piston 60 to rotate counterclockwise at slow, speed. Oil

When the tilting of the furnace "A' reaches the predetermined prepouring position, cam limit switch 106 opens to deenergizes solenoid 108. At this stage, bypass switch S5 is closed to reenergize solenoid 108, and actuator Al is rotated counterclockwise until cushioned stop 94 on piston 66 abuts against the internal cylinder wall This position is adjusted at a tilted crucible level approximately 15 below horizontal whereby the molten contents may be". completely emptied into the mold C. V I

Closing of switch S3 which is in series with normally closed cam limit switch 114 energizes solenoid 116 and causes rearward tilting of the furnace A. Solenoid 116 pushes the spool V2 to the left against the bias of centering springs 110 and 112 until the crossover channels couple inlet line 98 with line 102 and line 100 with the sump 96. Oil now flows through line 72 and into port 70 to force the piston 62 to the right. Piston 66 is caused to move to the left as a result of oilentering cylinder 68 through port 74 from line 76. Return of the oil from port is directed through line 82 down through line and back to the sump. When the crucible A reaches an erect position cam limit switch 114 opens to stop further rotation because of deenergization of solenoid 116. Thereafter, further slow backward tilting of the crucible is effected by closing bypass switch S6 until adjustable stop 84 is abutted by piston 66. Approximately 22 of backward-tilt is permitted in order to melt back any hardened crust of, cooled metal at the rear surface of the metal in the crucible. The total angle of pivotal motion of the crucible A is approximately 127.

In order to produce quick tilting of the crucible A, switch S4 is depressed to as to energize coil .120 of solenoid operated valve V3 Actuation of the coil urges the spool of the twoway valve V3 to the left against the .biasof spring 122. in this position, oil in 124 is coupled to hydraulic line 126 which feeds port 80 through line 82. Similarly, line 128 is coupled to the, tank 96 whereby oil from

ports

70 and 74 may be emptied through the valve V3 into the tank. Line 124 includes a needle valve 130 which is adjusted to permit approximately 250 cubic inches per minute of oil flow from the pumP. At this flow rate, forward pivoting the crucible A is produced through an angle of 90 in approximately one half second. Again, cushioned internal stop 94 takes up the shock when the crucible A reaches its pouring position at 105 forward tilt.

Finally, there is available a very rapid forward tilt speed which the molten metal in the crucible may be literally thrown into the molds C. In the throw speed, pushbutton switches S4 and S5 are simultaneously depressed whereby valve V3 is actuated to the left and valve V2 is actuated to the right, as shown in FIG. 6. Under such circumstances, line 126 is connected to the low rate of flow line 124 while at the same time line 100 is connected to the low rate of flow line 98. Accordingly, oil will be delivered to port 80 at a rate of flow of approximately 340 cubic inches per minute so that the crucible A may be emptied by tossing the molten metal therefrom.

It is to be observed that depression of any of the pushbutton switches S2 to S6 causes actuation of the corresponding valve.

V2 or V3. Since the rate of flow of oil in the

respective lines

98 and 130 has been previously adjusted by needle valves 104 and/or 130, the delivery to the rotary actuator A1 produces a predetermined speed of rotation thereof. Accordingly, tilting of the crucible A can be exactly duplicated on each successive operation and afford uniformity in molding of each batch.

In the aautomatic position of selector switch S1, the entire sequence of operations is performed automatically. Referring to the across-the-line diagram of FIG. 6, a timer T is con nected in series with the contacts of temperature controller 14, with contacts of vacuum sensing indicator controller 16, and with switch actuator 131 which closes when the mold C is elevated into proper position when all three conditions are cles the tilting of the furnace A in a predetermined program.

The automatic program begins with the furnace A at upright or zero position. When the molten metal 22, is at proper temperature, back tilt contacts 132 are fast closed to rock the crucible rearwardly to'melt back the hardened doughnut of metal at the rear of th crucible. The back tilt contacts 132 are in parallel with pushbutton switch S6 but bypass selector switch Sls semiauotmatic positions so that closure of the 132 contacts energize solenoid coil 116. Valve V2 is thrown to the left and the crucible A tilts backwardly until stop 84 is abutted and timer contacts 132 run out. At this stage, the furnace is canted rearwardly at approximately 22: Hardened or cooled crusted metal in the form of a doughnut is thereby melted back at the rear surface.

Next the rotation of the timer motor T causes actuation of contacts 134 which bypass the push button switch S2 but are in series with cam limit switch 106. The crucible A is thereby rocked forwardly at a predetermined speed into a prepouring position at approximately forward tilt, The crusted metal at the forward portion of the crucible is thereby melted back, the 20 forward tilted position is determined by opening of the cam limit switch 106 just before timing out of contacts 134. Immediately thereafter, the cam of the timer T actuates quick tilt contacts 136 which are in series with coil 120 but bypass pushbutton switch S4. Accordingly, the crucible is quick tilted forwardly at a rapid rate to pour its contents into the mold. At the end of this this position, the furnace will be tilted forward at a l05 angle. When cushion stop 94 contacts its abutment, timer contacts 136 run out. The end of the cycle occurs when the timer motor advances to actuate return contacts 138 which are in series with cam limit switch 114 and bypass pushbutton switch S3, Accordingly, the crucible A will rotate rearwardly until cam switch 114 opens at the vertical or zero position of the crucible.

At any portion of the cycle, the selector switch S1 can be moved to manual whereby the operator can rotate the crucible in either direction by turning handwheel 46. In manual position the switch S1 is adjacent the handwheel functions as a safety interlock and opens the electrical circuit so as to disengage the hydraulic valves.

To perform the tilting functions at a controlled predetermined repeatable speed through the use of pushbuttons, switch S1 is tumed to semiautomatic. Immediately, coil 86 is energized and valve V1 is actuated to blocking position. Manual operation is thereby prevented since hydraulic fluid cannot pass to either side of the rotary actuator Al except by operation of valves V2 or V3. Pushbutton S2 may be depressed for slow tilting forwardly until cam limit switch 106 stops the furnace at prepouring position. Thereafter, controlled forward tilt to empty the crucible at duplicatable speeds is accomplished as follows:

Depress pushbutton S5 for slow tilt,

Depress S4 for quick tilt, and

Depress botb$4and S5 for throw.

.In order to return'the furnace to upright position, pushbutton S3 is depressed until cam limit switch 114 is opened. To

. slow back tilt the fumace, pushbutton S6 is depressed. In

order to return the frfmace from back tilted position to upright, depress pushbutton S5 until furnace travels beyond the upright position. Then return to upright by depressing pushbutton S3.

Although this invention has been described in considerable 'detail, such description is intended as being illustrative rather than limiting, since the invention may be variously embodied, and the scope of the invention is to be determined as claimed.

I claim: 1. Apparatus for controlled tilting of a metallurgical furnace at predetermined duplicatable speeds comprising:

pivotal means for supporting the furnace about a horizontal axis;

means constituting a rotary hydraulic motor coupled with said pivotal means;

directionto said hydraulic motor to produce forward tilt- 75. conduit means for carrying hydraulic fluid in a first ing of said furnace and in a second direction to produce reverse rotation thereof; 1

first means for delivering hydraulic fluid at a predetermined rate of flow to said conduit means;

first valve means for selectively directing the hydraulic fluid in the first direction through said conduit means, closing off the supply of hydraulic fluid to said conduit-means, and directing the hydraulic fluid in the second direction through said conduit means;

second means for delivering hydraulic fluid at a second.

faster predetermined rate of flow to said conduit means;

second valve means for selectively directing the hydraulic fluid from said second means for delivering to said conduit at the second faster rate of flow, and closing off the supply from said second means for delivering; z first switch means for electrically actuating said first valve means for directing hydraulic fluid at the first rate of flow and in the first direction through said conduit means; second switch means for electrically actuating said first valve means for directing hydraulic fluid at the first rate I of flow and in the direction through said conduit means; third switch means for electrically actuating said second valve means for directing hydraulic fluid at the second rate of flow and in the first direction through said conduit 1 means; and whereby the furnace may be tilted forwardly at a repeatable slow speeds by actuation of said first switch means, at repeatable quick speeds by actuation of said third switch means, and at repeatable throw speeds by simultaneous actuation of said first and third switch means.

2. The apparatus of claim 1 wherein the horizontal axis of said pivotal means for supporting said furnace is adjacent the pouring nose thereof.

3. The apparatus of claim 1 including manual means for turning said furnace by hand.

4. The apparatus of claim 3 including third valve means in said conduit means for locking said manual means in operable position, and selector switch means for actuating said third valve means.

5. The apparatus of claim 1 including a first limit switch for automatically stopping the forward tilting of the furnace at a predetermined prepouring position during actuation of said first switch means, and fourth switch means bypassing said first limit switch for electrically actuating said first valve means.

6. The apparatus of claim 5 including a second limit switch for automatically stopping the rearward tilting of the furnace at an upright position during actuation of said second switch means.

7. The apparatus of claim 6 including fifth switch means for I electrically actuating said first valve in the second direction bypassing said second limit switch.

8. The apparatus of claim 1 including timer means for automatically cycling the tilting of said furnace. 9. The apparatus of claim 8 wherein said timer means first actuates the rearward tilting of said fumace from an upright position to a predetermined back tilted position by actuating said first valve means in the first direction, next actuates the quick forward tilting of said furnace to an emptying position by actuating said third switch means, and finally actuates the return of said furnace from the emptying position to the upright position by actuation of said first valve means in the 5 second direction.

10. The apparatus of claim 9 including means for heating said furnace, means for measuring the temperature of molten metal therein, a chamber for enclosing said furnace, means for mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,554,522 Dated January 12, 1971 Invent9r(g) Henry 0. Herrmann It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

m1 column 1 line 5, "duplicating" should be duplicatable In column 1, line 62, "line" should be lines In column 1, line 72, after "refined" insert and In column 2, line 3, "They" should be the In column 2, line 13, after "83" insert for In column 2 line 31, "pyromter should be pyrometer In column 2, lines 40 and 41, "trunnions" should be above In column 2 line 53, "bushing" should be bushings In column 2, line 55, after "chamber" delete "B" and insert a period. In column 3, line 3, after "60" insert is In column 3, line 6, after "68" insert and In column 3, line 18, after "by insert the In column 3, line 19, "54" should be S4 In column 3, line 25, "ties" should be its In column 4, line 1, after "64" insert and In column 4, line 8, "deenergizes" should be deenergize In column 4, line 36, after "V3" insert a period. In column 4, line 38, after "oil" "in" should be line In column 4, line 43, "pumP" should be pump P In column 4, line 49, before "which" insert in In column 4, line 54, "low" should be high In column 5, line 1, "run" should be turn In column 5, line 4, "22 should be therein In column 5, line 9, "semiauotmatic" positions should be "semiautomatic" position In column 5, line 20, after "tilt" change the comma to a period. In column 5, line 28, after "this" delete the second "this". In column 5, line 30, after "136" insert also In column 6, line 21, before "direction" insert second and after "means;" insert and, |I r 1 column 6, line 25, after "means;" delete and".

. P0-1050 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No- 3,554,522 Dated Taiwan/12,1971

I Henry 0. Hen'mann It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In column 6, line 26, before "repeatable" delete "a" In column 6, line 37, "operable" should be inoperable In column 6, line 51, after "valve" insert means In column 6, line 58, "first" (second occurrence) should be second same line, after "direction," insert then actuate the forward tilting of said furnace to a predeterminer pre-pouring position by actuation of said first valve means in the first direction,

In column 6, line 74, "in" (first occurrence) should be is Signed and sealed this 11th day of May 1971.

(SEAL) Attest:

EDWARD M.FIETGHER,JR. WILLIAM E. SCHUYLEE Attesting Officer Commissioner of Pat

Claims

1. Apparatus for controlled tilting of a metallurgical furnace at predetermined duplicatable speeds comprising: pivotal means for supporting the furnace about a horizontal axis; means constituting a rotary hydraulic motor coupled with said pivotal means; conduit means for carrying hydraulic fluid in a first direction to said hydraulic motor to produce forward tilting of said furnace and in a second direction to produce reverse rotation thereof; first means for delivering hydraulic fluid at a predetermined rate of flow to said conduit means; first valve means for selectively directing the hydraulic fluid in the first direction through said conduit means, closing off the supply of hydraulic fluid to said conduit means, and directing the hydraulic fluid in the second direction through said conduit means; second means for delivering hydraulic fluid at a second faster predetermined rate of flow to said conduit means; second valve means for selectively directing the hydraulic fluid from said second means for delivering to said conduit at the second faster rate of flow, and closing off the supply from said second means for delivering; first switch means for electrically actuating said first valve means for directing hydraulic fluid at the first rate of flow and in the first direction through said conduit means; second switch means for electrically actuating said first Valve means for directing hydraulic fluid at the first rate of flow and in the direction through said conduit means; third switch means for electrically actuating said second valve means for directing hydraulic fluid at the second rate of flow and in the first direction through said conduit means; and whereby the furnace may be tilted forwardly at a repeatable slow speeds by actuation of said first switch means, at repeatable quick speeds by actuation of said third switch means, and at repeatable ''''throw'''' speeds by simultaneous actuation of said first and third switch means.

7. The apparatus of claim 6 including fifth switch means for electrically actuating said first valve in the second direction bypassing said second limit switch.

8. The apparatus of claim 1 including timer means for automatically cycling the tilting of said furnace.

9. The apparatus of claim 8 wherein said timer means first actuates the rearward tilting of said furnace from an upright position to a predetermined back tilted position by actuating said first valve means in the first direction, next actuates the quick forward tilting of said furnace to an emptying position by actuating said third switch means, and finally actuates the return of said furnace from the emptying position to the upright position by actuation of said first valve means in the second direction.

10. The apparatus of claim 9 including means for heating said furnace, means for measuring the temperature of molten metal therein, a chamber for enclosing said furnace, means for evacuating said chamber, means for measuring the pressure in said chamber, an interlock for said chamber, means for introducing a mold through said interlock into a predetermined position for receiving the contents to said furnace during discharging thereof, and means for actuating said timer means when the temperature of the metal and the pressure in the chamber have reached a predetermined level and when the mold in in predetermined position.