US3152206A - Quick connect vacuum system - Google Patents

Description

AOei. 6, 1964 H. s. PHILBRICK, JR

QUICK CONNECT VACUUM SYSTEM 4 Sheets-Sheet 1 Filed April s, 1961 w, gw C Oct. 6, 1964 H. s. PHILBRICK, JR 3,152,206

QUICK CONNECT VACUUM SYSTEM Filed April 3, 1961 4 Sheets-Sheet 2 Weke# x Oct. 6, 1964 H. s. PHILBRICK, JR 3,152,206

QUICK CONNECT VACUUM SYSTEM Filed April 5, 1961 4 Sheets-Sheet 3 INV EN TOR.

Oct. 6, 1964 H. s. PHILBRIQIQJR QUICK CONNECT VACUUM SYSTEM 4 Sheets-Sheet 4 Filed April 3, 1961 United States Patent O psi rfhis invention relates to vacuum tank systems, and particularly to a multiple tank system for continuously degassing ladles of molten metal.

In recent years more and more steel is being degassed in order to remove included deleterious gases such as oxygen, nitrogen and hydrogen. The usual mode of degassing molten metal is to subject a ladle of it to a vacuurn, either alone or in combination with other processes.

Although the quality of steel is considerably increased the process does create some problems. The length of time the molten metal is in transit between the furnace and ingot molds is lengthened. This increased time may necessitate adding superheat to the molten metal, and superheating tends to wear out furnace linings at a faster than normal rate.

A substantial portion of the increased time is consumed in connecting the vacuum tank to the vacuum system after the ladle is placed in the tank, and then pumping down the tank and system to a vacuum sufticient to effectively degas the metal.

It is now customary to install a complete vacuum system for each vacuum tank which is to be used for degassing. lf a plurality of tanks are to be used for degassing, the cost of installing degassing systems is multiplied by the number of units required. Likewise, the iloor space needed to install the systems is increased by the number of units put in operation.

Accordingly, a primary object of this invention is to provide a vacuum tank system especially adapted for degassing molten metal in which a vacuum tank or a vacuum tight molten metal receptacle such as an open hearth bottle car is immediately connected to a vacuum system as soon as the tank cover or degassing hood is put in piace to thereby reduce the connecting and pump-down time.

Another object is to provide a very ilexible vacuum tank system in which a single vacuum tank hood asser bly, a single lift-and-swing device, and a single vacuum system are arranged to service a plurality of vacuum tanks.

Another object is to provide a vacuum tank hood assembly for a vacuum system, said hood assembly having a pair of outlets, each outlet being connectable alternately to an ejector system, the other outlet being automatically blanked od whenever it is not in use.

Y et a further object is to provide a vacuum tank system requiring a minimum initial investment.

Yet another object is to provide a vacuum tank system in which production need not be discontinued due to maintenance or break down of a vacuum tank.

A further object is to provide a vacuum tank system which can be continuously operated, one tank in the system being used while a second tank is being prepared for the next use.

Yet another object is to provide an open hearth degassing plant in which molten metal in a vacuum tight bottle car is degassed between the furnace and ladle filling pit.

A further object is to provide an open hearth bottle latenteel @ein 6, l

car degassing unit in which a bottle car may be quickly connected to a vacuum system to thereby minimize ternperature drop between the open hearth furnace and ladle.

Another object is to provide an open hearth bottle car egassing unit which can be easily incorporated into an existing open hearth operation.

Other objects and advantages will become apparent from a reading of the following description of the invention.

The invention is illustrated more or less diagrammatically in the accompanying drawings wherein:

FIGURE l is a top plan View of the system;

FIGURE 2 is a side elevation of a portion of the system taken substantially along the line 2-2 of FIGURE l with parts broken away for clarity;

FIGURE 3 is a top plan View to a smaller scale than that of FIGURES l and 2 illustrating the vacuum tank hood assembly, parts being broken away for purposes of clarity;

FIGURE 4 is a side elevation of FIGURE 3 with parts broken away for purposes of clarity;

FIGURE 5 is a view taken substantially along the line 5-5 or" FIGURE 3;

FIGURE 6 is a top plan view of another embodiment of the invention; and

FlGURE 7 is an elevation taken substantially along the line of FIGURE 6.

Like reference numerals will be used to refer to like parts throughout the following description of the drawings.

The general assembly is illustrated best in FIGURES 1 and 2. In FIGURE l a pair of vacuum tank units are indicated generally at lll and lll. Each unit consists of a vacuum tank l2 which consists of a vertical wall portion i3 Welded at its lower end to a base plate M which in turn rests on foundation l5. The joint between wall 13 and foundation plate i4 is air-tight as are all other jonits in the system. ri`he tank is large enough to accommodate a commercial sized container of molten metal, in this case a ladle le which may contain anywhere from 2 to 100 tons of molten metal. Since the construction of the tank itself and the means for supporting and centering the ladle are not essential to an understanding of the invention, they are not further illustrated or described.

The upper edge of tank wall 13 terminates in a pair of flanges I7 and i3. Upper flange 1S is suitably apertured to receive a seal l.

A cover or hood assembly is indicated generally at 2%. It consists of a dome 2l which terminates at its lower edge in a sealing flange 22. Flange 22 is suitably apertured in opposition to the aperture in flange il@ so that a seal carried by the flanges forms an air-tight seal between the meeting surfaces. A header Z4 is secured to the cover 2l by welding at 25. The header includes a long horizontal run 26, a pair of elbows 27 and Ztl, and a pair of vertical runs 29, 3%. A pair of reinforcing braces 3l, 3?; are welded at their outer ends to the elbows and vertical runs and to their inner ends to the cover. The braces stabilize the header with respect to the cover. The lower end of each of runs 2', is welded to a sealing flange 33, 34 respectively. Each flange is apertured, as at 35, in line with the internal passage of the header. Extension of flanges 34, 33 are welded to Harige 22.

A blank stand is indicated at 37. The stand consists of a pipe welded at its lower end to a plate 38 which rests on the foundation 15. A solid blank ange 39 is head assembly is set in place.

Y melt and the gases withdrawn from the ladle.

welded to the upper end of the pipe, the upper surface of blank ange 39 lying in the same plane as the upper surface of flange l. When the hood assembly is set in place over the vacuum retort, sealing ange 34 will contact blank ilange 39 at the same instant cover flange 22 contacts tank frange i8. Arly suitable sealing means may be utilized to provide an air-tight seal between the header 3d and blank ilange 39.

A vacuum system inlet pipe is indicated at l ipe @il has a sealing ange 4l Welded to its upper end, the ange being aligned with ange 33 of run 3@ when the ln this instance the elevation of the upper surface of sealing ange el is substantially identical to the elevation of the lower surface of llange 33. Any suitable sealing means is provided to form an air-tight seal between the flanges.

A short collar d2 connects pipe d to a vacuum valve 43. rl`he vacuum valve in turn connects the tank unit to a pump-down system indicated generally at 4d in FlG- URE l. Any suitable vacuum system can be used with the illustrated tank unit. In this case a steam ejector system is illustrated. lipe 45 represents the first stage of a multiple stage system.

The dimensions of the unit, particularly the elevation of the upper surfaces of each of flanges 39 and 4l, are stabilized by the reinforcing structure indicated generally at d'7 and 4d. These stabilizing structures are essentially repeated on tank unit lll, and accordingly only tank unit 11 and FIGURES l and 2 will be referred to.

Each of the stabilizing structures consists of a pair of generally vertically oriented plates d?, t?, arranged to lie along an extension of the diameter of each tank. rhe inner end of the shorter of the two plates 4%, is welded to the outside of tank wall 13. The outer end of the plate is Welded to a Vertical iiange 5l. The inner end of each of plates 59 is welded to a second vertical frange 52. The outer end of each of vertical plates 5d is welded to the blank stand 37 and discharge pipe i9 respectively. A rib S3 on outer plate 52 lits into a mating groove on plate 5l. and prevents the plates from twisting due tordistorting forces set up by heat given otf from the ladle. A piurality of generally horizontally oriented reinforcing plates 5d, 5S, 56, 5'7 provide additional stability. The generally horizont-ally oriented reinforcing plates of tank unit lil corresponding to plates S and 55 in tank unit ll. will,

' of course, be so located as to avoid interference with one another.

The vacuum hood assembly and means for positioning it are illustrated in more detail in FGURES 3, 4 and 5. The header 2d is lined with refractory o@ which protects the metal shell 6l from direct exposure to the heat of the Hood 2l is apertured as at 62 and 63 in line with a pair of mating openings 6d, 65 in the lower portion of header run 2o. Reinforcing plates 62a and 63a are welded to the inside of the dome shell. Gases withdrawn from the ladle of molten metal can therefore leave through either of openings 62 or 63. in the position of the hood assembly illustrated in FGURES l and 2, the bulk of the gases will be withdrawn through opening 62, 64. When the hood assembly is rotated ninety degrees to overlie tank unit l0, the bulk of the gases will be withdrawn through opening 63, 65 and leave the tank unit through run 29 which will then be connected to the outlet pipe 4d.

A short pipe on which terminates in a sealing flange 67 opens into the long run 26 in line with the center line of the tank. lt is large enough to permit the insertion and removal of a met-al sampling device or to admit alloyingelements and/or charge materials to the melt. It is indicated more or less diagrammatically, but it will be understood that in an actual setup it will be suitably the upper end of the pipe.

The rib locks one plate to the other The hood assembly is moved back and forth between the tank units by a lift-and-swing device indicated generally at '763. In this instance, the lift-and-swing device is a vertically extendable and reciprocable ram which raises and lowers the entire assembly, and a horizontally positioned cylinder which rotates the hood assembly in a horizontal plane.

The hood assembly is connected to the ram by a supporting structure illustrated best in FIGURES l, 3 and 5. The supporting structure consists essentially of a pair of generally vertically oriented side plates 7l, 72, shown est in FIGURES 3 and 5, which are welded at their inner ends to the lift-and-swing device, as at 73, and at their outer ends to the outer shell of the hood assembly, as at 74. A pair of top and bottom plates '75, 76 likewise extend between the collar 7th: of the lift-andfswing device and the tank to provide additional rigidity. The forwardmost end 77 of top plate 75 is curved upwardly and lies flat against the upper surface of the outer shell till of the hood. Three vertical reinforcing brackets 7S, 79 and Sil provide additional support.

Any suitable means may be utilized to rotate the hood assembly so as to align it with either tank unit lil or 1l. In this instance, a hydraulic cylinder indicated diagrammatically at 34 has been shown. The cylinder is pivoted as at 8l to a stationary support 82. The outer end of the piston rod 3 is pivotally connected to side plate 72. The swinging piston is indicated only diagrammatically as it will be understood that any suitable device, such as a mechanical linkage or a worm gear, for example, could be utilized to swing the hood assembly from one position to another.

ln FIGURES 6 and 7, an open hearth degassing plant is illustrated. In FlGURE 6, a degassing station is indicated generally at 86. A rst molten metal transfer car, in this instance, a conventional bottle car, is indicated generally at 87, and a second bottle car is indicated generally at S8. Car S8 is at a ladle lling station, indicated generally at S9. The bottle cars move from station to station Y along tracks 90. The bottle cars are shown in this instance as self-propelled, but it will be understood that within the scope of the invention the rnolten metal transfer cars may be either self-propelled or moved from station to station by other power means. A charging station, which includes an open hearth furnace and means for tapping molten metal from the furnace into the bottle car, would be located just to the left of degassing stationv 8o with reference to FGURE 6. Since the details of the charging station are conventional, it is not further illustrated or described,

Referring now to FIGURES 6 and 7, a closed, vacuum tight tank is indicated at 91. The right end of the tank opens into a conduit 92 which is connected to a vacuum system, not shown. Arrow 93 indicates the fluid ow path through tank 9i when the degassing station is in operation. Since the details of the vacuum system are conventional, they are not furthe-r illustrated or described.

A multi-stage steam ejector system may advantageously be used.

The left end of tank 9i opens into an upstanding conduit 94 which terminates at its upper end in a sealing ange 95. Flange 95 is constructed to make sealing engagement with a similar llange 96 carried at the lower end of a vacuum connection or conduit indicated generally at 97. Vacuum conduit 97 consists essentially of a short horizontal run of pipe 98, an elbow 99, a short collar 100 which terminates in flange 96, and another short collar lill which terminates at its lower end in a sealing ange 102.

Vacuum conduit 97 is welded or otherwise suitably secured to a rectangular frame which consists essentially of longitudinal channels 103, 194 and cross channels E65,

Y 106. The frame, in turn, is connected by four hydraulic rams 167, fillet, 169, lill to a supporting structure indicatedgenerally at lill. Suitablehydraulic lines under control of a single master valve admit hydraulic fluid to the cylinders to raise and lower the frame and vacuum conduit through horizontal planes. A series of rollers 112, 113 carried by the rectangular frame roll along one of the legs of a series of guide members 114, 115 to help maintain the frame and vacuum conduit horizontal during raising and lowering movement.

Bottle car S7, which is essentially a vacuum enclosure suitable for containing up to around 200 tons of molten metal, consists essentially of a tank portion 121? which is bodily rotatable about trunnions 121, 122 by large bull gears 123, 124. A short neck 125, which terminates at its upper end in a sealing flange 126, surrounds an opening in the top of the bottle car when it is in its normal position. Flange 126 meets with flange 1ii2 and the two flanges form a vacuum tight seal when in engagement.

Referring now to FlGURE 6, a second bottle car is shown lling a ladle 13@ at the ladle lling pit or station 89. The car has been rotated approximately 90 degrees to a position in which molten metal may be discharged through the opening defined by neck 12S.

The ladle may be of any conventional size and, accordingly, it is not illustrated in detail. A pair of lifting trunnions are indicated at 132, 133 and a stopper rod carrying arm is indicated at 134. It will be understood that a stopper rod, not shown, seats in a discharge nozzle 135 in the bottom of the ladle. The framework of the pit is indicated at 135.

It will be understood that the exact construction of the vacuum connection surrounding the opening of the bottle car can be varied within the scope of the invention. In this instance the actual opening is indicated at 137, and the neck 125 is oblong in shape, as can best be seen from the figures.

The use and operation of the invention is as follows.

The hood assembly 2lb is elevated to the position of FIGURE 4 by the lift-and-swing device 7l?. Assume that the assembly is swung to a position in which it substantially overlies tank unit 1li. A ladle of molten metal 16 is then lowered into position within tank As soon as the ladle is positioned, the swinging cylinder de is actuated to swing the entire hood assembly into the position of FIGURE l, overlying tank unit 11. lt will be understood that any conventional means may be utilized to insure that the hood is directly aligned with the flange 13 of the lower portion of the vacuum tank. Vertical runs 29 and 3l? of the header will then be precisely aligned with stand 37 and pipe di? respectively. The lift-and-swing device lowers the hood assembly into the position of FIGURE 2. Since the meeting surfaces of flanges 33 and 41, 34 and 39, and 22 and 1S lie in the same plane, they will all make sealing contact simultaneously as the hood assembly comes to rest in the position of FGURE 2. Since flange 39 is solid and a seal is formed at the joint between lianges 34 and 3?, the conduit 29 will be blanked off as soon as the hood settles in place. If flange 18 is carried by the hood assembly and a sealing surface is formed between flanges 17 and 18, a closed system will again be formed as soon as the hood assembly is lowered into place because the parts will be so dimensioned that all will meet simultaneously.

Although flanges 33 and 34 are illustrated as lying in parallel, coincident planes, the invention is not limited to this particular relationship of the mating surfaces. It may be expedient, depending on operating conditions or other factors, to arrange thee flanges in parallel, noncoincident planes. Such a setup is illustrated in FIG- URES 6 and 7. 1t is even within the scope of the invention to arrange the surfaces to meet in non-parallel planes. The machining is facilitated by the parallelism of the planes however. The really important fact, irrespective of the relationship of the orientation of the meeting planes with one another, is that the flanges engage simultaneously or with only a very small lag.

As soon as the hood comes to rest on the top of the tank 12, vacuum valve 43 is opened and the entire tank unit is immediately connected to the ejector system. Gases are withdrawn from the tank and molten metal through openings 62 and 63 in the hood. The bulk of the gases will pass out of the tank and molten metal through opening 62 and go directly into the vacuum system through header 24, elbow 23, run 3l?, collar d2 and valve 43. Some gases will, of course, pass out through opening 63 into header 24.

As soon as the molten metal is treated, hood assembly 2li is raised, swung over tank unit 1t), and ladle 16 removed. The hood assembly is then swung back over tank unit 11, another laddle placed in tank unit lll, and the hood assembly is then placed on tank unit 1li. Tank unit 11 is then allowed to cool down until the third ladle of molten metal is ready for treatment. Tank unit 1li will, of course, cool while the third ladle is being treated in tank unit 11. Ladles of molten metal may thereby be continuously degassed.

When the header assembly is swung to a position in which it overlies vacuum tank unit 10, the mode of operation will be exactly the same except in this case the bulk of the gases will be withdrawn through opening 63 since that opening will then lie in the shortest path between the vacuum tank and vacuum system inlet pipe 49.

In the operation of the embodiment of FIGURES 6 and 7, molten metal from an open hearth furnace at a charging station is poured into a properly positioned bottle car by any conventional means. Pihe car is then moved to the degassing station 86. Hydraulic rams 1W, ldd, lll, 11i? are then actuated to lower framework 163, 1h14, 165, 136 carrying vacuum conduit 97 into the solid line position of FIGURE 7. Vacuum conduit flanges 102, 9e mate with flanges 126 and 95, respectively. The anges are so dimensioned that contact is made substantially simultaneously between the two sets of flanges so that a vacuum can immediately be commenced to be drawn through conduit 92. In this instance, the mating surfaces are in parallel, but not coincident, planes.

After degassing is completed, the hydraulic rams are again actuated to elevate the Vacuum connection to the dotted line position of FIGURE 7. The vacuum conduit is maintained in horizontal planes throughout its upward and downward movement by virtue of the rolling of rigid framework 193, 1M, 195, 1516 along the guide members 114, 115.

After the molten metal has been suiiiciently degassed and the vacuum conduit raised to a position in which it clears the bottle car, the car is then moved to the ladle filling station shown at the right in FIGURE 6. The bull gears are then actuated and the car rotated degrees about its axis to pour into a ladle 139.

Although a preferred embodiment of the invention has been illustrated and described, it will be understood that various other modifications may be made within the scope of the invention. Accordingly, it is intended that the descripuon and drawings be considered illustrative only and that the scope of the invention be limited only by the scope of the following claims.

I claim:

l. A vacuum system for vacunadegassing molten metals, said system comprising a pair of vacuum tanks, said tanks being open at their upper ends,

a hood assembly, said hood assembly including a hood engageable with the upper open end of each tank and adapted, when in engagement with a tank, to form an air-tight seal therewith,

a header, said header having an inlet opening into the hood and a pair of outlets, each outlet being connectable, in turn and depending upon the position of the hood assembly, to

a vacuum system inlet,

a lift-and-swing device, said lift-and-swing device comprising a ram and a supporting arm extending from the ram to the hood assembly, said ram being located substantially equidistantly from each tank, said hood assembly being swingable, in response to actuation of the lift-and-swing device, about the ram as a pivot, the outlet of the header and the hood assembly being so arranged as to make simultaneous connection with the vacuum system inlet and vacuum tank, respectively, when the ram lowers the hood assembly into place on the vacuum tank, and, means for blanking olf the header outlet not connected to the vacuum system inlet at the same time as the other outlet is connected to the vacuum system inlet, said means including at least one closure member so disposed as to blank oif the unused header outlet. 2. The vacuum system of claim 1 further characterized in that the means for blanking o the unused header outlet includes a plate carried by a support structure, said plate having a surface complementary to the unused header outlet, said plate, vacuum system inlet and open end of each vacuum tank lying in the same plane so that all meeting surfaces engage simultaneously as the ram lowers the hood assembly into place.

3. A vacuum system for degassing molten metal, said system including at least a pair of open ended vacuum enclosures, a hood assembly engageable with the open end of each enclosure alternatively, means for forming a vacuum tight seal between the meeting surfaces of the hood assembly and an enclosure when they are in engagement with one another, said hood assembly having an opening therethrough connected to a header movable with the hood assembly,

means forming a vacuum tight seal between the hood assembly and the header,

said header in turn being connectable and disconnectable in vacuum tight engagement to a vacuum system inlet, said foregoing structure thereby forming, when in engagement, a closed vacuum tight system having an opening connectable to a vacuum system inlet,

means for relatively moving the hood assembly, and the header, from one enclosure to another whereby the hood assembly is aligned with an enclosure and the header with the vacuum system inlet,

said vacuum enclosure, vacuum system inlet, hood assembly, and header being so arranged that sealing engagement between the hood assembly and the vacuum enclosure, and sealing engagement between the header and the vacuum system inlet, occurs substantially simultaneously,

said vacuum enclosure, vacuum system inlet, hood assembly, and header being so arranged relative to one another that, after making sealing engagement, said sealing engagement is thereafter maintained until further relative movement occurs.

4. The vacuum system of claim 3 further characterized in that the open end of each vacuum enclosure and the vacuum system inlet lie in the same plane.

5. The vacuum system of claim 3 further characterized in that the means for relatively moving the hood assembly, and the header, from one enclosure to another, is a lift-and-swing device located between adjacent vacuum enclosures, said lift-and-swing device having a vertical lift device and a hood assembly supporting arm extending outwardly from the lift device into operative lifting engagement with the hood assembly, said hood assembly being pivotable about the left device, and a swing device operatively connected to the hood assembly for pivoting the hood assembly about the swing device, said lift device being located adjacent each vacuum enclosure so that the hood assembly and header outlet may be brought into registry with the vacuum enclosure and vacuum system inlet, respectively, as the hood assembly swings about the lift device.

6. The vacuum system of claim 3 further including dimension stabilizing means for insuring vacuum-tight engagement of the sealing surfaces irrespective of temperature variations in the system, said dimension stabilizing means comprising structural members connecting adjacent system components, including the header and the hood assembly, said structural members being disposed generally along an extension of a diameter of the components with which they are associated.

7. The vacuum system of claim 3 further characterized in that the header comprises a vacuum conduit forming a uid iiow path between the hood assembly and two header outlets, and

further including a pair of closure members so disposed as to make sealing engagement with the unused header outlet when the hood assembly and header are in sealing engagement with a vacuum enclosure, said closure members thereby blanking off the unused header outlet.

8. A system for degassing molten metal, said system including, in combination,

a vacuum enclosure having an opening therein, said enclosure being constructed and arranged to contain a quantity of molten metal to be degassed, a vacuum system, said vacuum system having an inlet, a vacuum connection, said vacuum connection having an inlet engageabie with the opening in the vacuum enclosure and an outlet engageable with the vacuum system inlet,

and movable means for operatively engaging and disengaging the vacuum connection with the vacuum enclosure and the vacuum system to thereby provide a gastight fluid iiow path from the vacuum enclosure, through the vacuum connection and into the vacuum system,

said ..-'acuum enclosure, vacuum system inlet, and vacuum connection being so arranged that sealing engagement between the vacuum enclosure and the vacuum connection, and sealing engagement between the vacuum system inlet and the vacuum connection occurs substantially simultaneously.

9. A vacuum system for degassing molten metal in a plant of the type having a furnace constructed and arranged to discharge to a molten metal transfer car, a degassing station for degassing molten metal in a transfer car, a ladle lling station for pouring degassed molten metal from the transfer car into a receptacle such as a ladle, and a molten metal transfer car and means for moving the transfer car from station to station, said degassing station including a vacuum system inlet, a vacuum conduit for connecting the transfer car to the vacuum system inlet, and movable means for making alternate engagement and disengagement between the transfer car and vacuum conduit and between the vacuum conduit and the vacuum system inlet, the engaging surfaces of the vacuum conduit, transfer car and vacuum system inlet being so arranged as to make substantially simultaneous sealing engagement whereby a vacuum may be quickly drawn in the transfer car so that heat loss between the charging station and ladle filling station is kept at a minimum.

10. The vacuum system of claim 9 further characterized in that the means for making sealing engagement between the transfer car and vacuum conduit, and between the vacuum conduit and the vacuum system inlet, includes,

a support structure, and

hydraulic cylinder means carried by the support structure and operatively connected to the vacuum conduit to move said vacuum conduit into and out of substantially simultaneous sealing engagement with the metal transfer car and the vacuum system inlet, the meeting surfaces between the metal transfer car and the vacuum conduit, and between the vacuum 10 system inlet and the vacuum conduit being so posi- 2,290,961 Heuer July 28, 1942 tioned as to make substantially simultaneous en- 2,852,246 Janco Sept. 16, 1958 gagement When the vacuum conduit is moved into engagement with the metal transfer car and vacuum FOREIGN PATENTS system inlet. 5 1,087,534 France Aug. 25, 1954 References Cited in the le of this patent OTHER REFERENCES UNITED STATES PATENTS Making, Shaping and Treating of Steel, charts between 2,177,716 Heuer Oct. 31, 1939 pages 282-283 and 398, 399, 6th edition, 1951.

Claims (1)

1. A VACUUM SYSTEM FOR VACUUM DEGASSING MOLTEN METALS, SAID SYSTEM COMPRISING A PAIR OF VACUUM TANKS, SAID TANKS BEING OPEN AT THEIR UPPER ENDS, A HOOD ASSEMBLY, SAID HOOD ASSEMBLY INCLUDING A HOOD ENGAGEABLE WITH THE UPPER OPEN END OF EACH TANK AND ADAPTED, WHEN IN ENGAGEMENT WITH A TANK, TO FORM AN AIR-TIGHT SEAL THEREWITH, A HEADER, SAID HEADER HAVING AN INLET OPENING INTO THE HOOD AND A PAIR OF OUTLETS, EACH OUTLET BEING CONNECTABLE, IN TURN AND DEPENDING UPON THE POSITION OF THE HOOD ASSEMBLY, TO A VACUUM SYSTEM INLET, A LIFT-AND-SWING DEVICE, SAID LIFT-AND -SWING DEVICE COMPRISING A RAM AND A SUPPORTING ARM EXTENDING FROM THE RAM TO THE HOOD ASSEMBLY, SAID RAM BEING LOCATED SUBSTANTIALLY EQUIDISTANTLY FROM EACH TANK, SAID HOOD ASSEMBLY BEING SWINGABLE, IN RESPONSE TO ACTUATION OF THE LIFT-AND-SWING DEVICE, ABOUT THE RAM AS A PIVOT,

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