US3430644A - Rotary gate for bottom pour vessel - Google Patents

Description

March 4, 1969 Sheet of 2 Filed Feb. 24, 1967 FIG INVENTOR RICHARD EVANS LYMAN ATTORNEY March 4, 1969 R. E. LYMAN 3,430,644

ROTARY GATE FOR BOTTOM POUR VESSEL Filed Feb. 24, 1967 Sheet 2 of 2 O INVENTOR RICH AR'D EVANS LYMAN ATTORNEY United States Patent 0 3,430,644 ROTARY GATE FUR BGTTOM PGUR VESSEL Richard E. Lyman, Homewood, IiL, assignor to United States Steel Qerporation, a corporation of Delaware Filed Feb. 24, 1967, Ser. No. 618,367 US. Ci. 137329.tl6 3 Claims Int. Cl. Flair 3/ 08 ABSTRACT OF THE DISCLOSURE A bottom pour vessel for teeming molten metal has a refractory disc rotatably mounted externally on the bottom thereof. The disc has circumferentially spaced holes adapted to register successively with a discharge nozzle in the bottom of the ladle. The disc is supported in a metal tray secured to the ladle bottom. A spring urges the disc against the nozzle.

BACKGROUND OF THE INVENTION This invention relates to bottom pour vessels for teeming molten metal such as steel, and in particular to improved discharge valves for such vessels.

The discharge of steel from bottom pouring vessels has heretofore generally been controlled by a stopper rod in combination with a fixed nozzle set in the bottom of the vessel. This arrangement is not entirely satisfactory for controlling the teeming of steel into a continuously casting mold because the nozzle bore and the mating surfaces of the stopper rod head and the nozzle seat become eroded during extended periods of teeming with the result that the flow of liquid steel through the nozzle increases beyond the desired value and the stopper rod does not fit tightly enough against the nozzle seat to enable a positive shut-off of liquid steel flow. The protective refractory sleeves enclosing the stopper rod also became overheated by immersion in liquid steel and eroded from chemical action by molten slag during extended periods of teeming with the result that the rod itself may fail castastrophically making it impossible to shut off a flow of liquid steel. A further disadvantage of stopper rods is that they are difficult to install, maintain, and operate in fully enclosed bottom pouring vacuum degassing vessels.

A significant advance in the art of closure members of bottom pour vessels containing molten metal has been made recently in the development of a reciprocating valve located on the exterior of the vessel beneath the discharge nozzle. This reciprocating valve has a horizontally movable closure member which is capable of seating tightly against the outlet end of the nozzle so as to form a fluidtight seal and to prevent leakage of steel when the valve is closed. Another important advantage of the reciprocating valve is that it can be opened and closed much more quickly than a stopper rod. This makes it possible to control the level of molten steel in the mold much more effectively. A further advantage of the reciprocating valve is that it provides an effective closure member for bottom pouring continuous vacuum degassing vessels for the first time.

Although the reciprocating valve represents a significant step forward, it is not without its disadvantages. Chief of these is that it requires a larger amount of space, not only in the direction of travel of the valve but in the transverse direction as well so that it is not suitable for applications involving pouring streams in close proximity to each other. Furthermore, the reciprocating valve incorporates a sizeable number of springs, sliding members, pivoted members, and other critical mechanical components that are distributed over a large area of the bottom shell of the liquid steel vessel so that they are difi'lcult to protect from overheating and damage from liquidsteel splashing during teeming. In addition, this valve requires for reliable extended and repeated operation, the insertion of a repalcement sliding nozzle block each time the device is actuated. Because of this requirement the reciprocating slide valve would require the use of a cumbersome magazine arrangement to supply replacement nozzle blocks during remotely controlled operation.

SUMMARY OF THE INVENTION The teeming apparatus of this invention includes a vessel for containing molten metal having a bottom pour discharge nozzle and a novel rotary discharge valve mounted beneath the vessel for closing this nozzle, and an actuator for rotating the valve. The discharge valve comprises a refractory disc having a plurality of teeming openings which may be brought into alignment with the discharge nozzle by rotation of the valve, and a metal May which supports the refractory disc. The valve is mounted for rotation about its central axis and is held in fluidtight engagement with the outlet end of the discharge nozzle. The discharge valve of this invention is a compact structure, mounted on the exterior of the vessel for ease of maintenance and repair. This valve is capable of repeated opening and closing of the discharge nozzle in rapid sequence without dribbling or leakage of molten metal either as the discharge valve closes or after it has been closed. This valve is arranged to be easily protected from damage by splashing steel by a simple circular shield and all of its critical temperature-sensitive mechanical components are concentrated in an enclosed hub assembly where they are effectively air cooled. It is particularly suitable for use in applications involving closely spaced multiple pouring streams. Because it requires no replacements or adjustments during repeated opening and closing, this valve can be operated entirely by remote control.

BRIEF DESCRIPTION OF THE DRAWINGS This invention will now be described with reference to the accompanying drawings, in which:

FIGURE 1 is a front elevational view of a vessel for molten metal having a discharge valve of this invention;

FIGURE 2 is a plan view of the rotary valve of this invention and the mounting plate, on which this valve is monuted, looking upwardly along line 2-2 of FIG- URE 1;

FIGURE 3 is a vertical sectional view of the valve of this invention, taken along line 33 of FIGURE 2;

FIGURE 4 is a fragmentary plan view of a tray for containing the refractory closure member of this invention;

FIGURE 5 is a vertical sectional view of the tray taken along line 55 of FIGURE 4;

FIGURE 6 is a plan view, looking upwardly, of the mounting plate on which the valve is mounted, with the valve and the actuator therefor removed; and

FIGURE 7 is a detail vertical sectional view of a portion of the valve mounting and cooling structure, taken along line 7-7 of FIGURE 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIGURE 1, 10 is a vessel for containing molten steel and having a bottom pour discharge nozzle 11. Vessel 10 may be a ladle, a tundish, a vacuum degassing vessel, or other vessel for teeming molten steel. Such a vessel conventionally has a refractory lining and a metallic outer shell. The discharge nozzle 11 is opened and closed by a rotary valve 12, which rotates about its central axis. Rotary valve 12 includes a plurality of teeming openings, to be described hereinafter which may be aligned with nozzle 11 by rotation of valve 12, to permit teeming of molten metal from vessel 10. A valve actuator 13 (shown with a position broken away in FIGURE 1) rotates valve 12 to open and close discharge nozzle 11. This actuator 13 is mounted on a mounting plate 14, which is secured to the vessel by bolts which are stud welded to the bottom of the vessel.

The structure of rotary valve 12 will now be described with reference to FIGURES 2 to 5. Valve 12 includes a metal tray 20, best shown in FIGURE 5, having a cen tral opening 21 surrounded by an upstanding boss 22, and a plurality of teeming openings 23 located at equal radii from the central axis of the tray. Extending around the periphery of tray is an upstanding side wall 24 which terminates in an outwardly extending flange 25. Flange 25 has a plurality of openings 26 which receive pins 27, which are engaged by the actuating mechanism 13 to rotate the valve 12. There are twice as many openings 26 and pins 27 as there are teeming openings 23, so that each stroke of the actuator 13 will move the valve from open to closed position, or vice versa. Tray 20 also includes a plurality of upstanding partitions 28 extending from boss 22 to side wall 24 and dividing the tray 20 into a plurality of sectors, each of which has one teeming opening 23.

A refractory closure member 30 supported :by tray 20 has a central opening which receives boss 22 of tray 20. Closure member 30 also has a plurality of nozzle inserts 32 which are aligned with teeming openings 23 in tray 20. The nozzle inserts 32 are sleeves of a hard, dense refractory having high resistance to erosion by molten steel flowing therethrough and having greater heat resistance than the disc 30. The refractory inserts preferably have slightly tapered bores through which molten metal is teemed. Inserts 32 can be easily replaced when eroded without replacement of refractory closure member 30. Closure member 30 has channels which receive the partitions 28 in tray 20. The upper surface 34 of member 30 is smooth in order to provide a fluid-tight closure with low friction as the valve 12 is rotated.

Mounting plate 14 may be seen most readily in FIG- URES 2, 3, and 7.

This mounting plate is a metallic plate having a main portion 41 of substantially rectangular shape, slightly longer and narrower than valve 12, beneath which valve 12 is mounted, and a narrower portion 42 at an angle to the longitudinal axis of the main portion 20, on which valve actuator 13 is mounted. Several openings 43 for bolts 15 are provided. The plate 14 includes a pair of large circular openings 44 and 45 and a smaller circular opening 46 therebetween, all three openings having their centers along a straight line. Plate 14 is mounted on vessel 19 so that the center of opening 44 coincides with the axis of discharge nozzle 11. A refractory insert 47 having a central tapered bore 48 is placed in opening 44, which has a shoulder to support the insert. The inlet end of bore 48 has the same diameter as the bore of nozzle 11, and is aligned therewith. The outlet diameter of bore 48 is equal to the inlet diameters of the bores 33 in nozzle inserts 32. The upper face of refractory insert 47 rests against the tip of discharge nozzle 11. Refractory insert 47 is in effect a continuation of discharge nozzle 11, and the outer face of insert 47 provides the outlet end of the discharge opening. This outer surface, which is smooth, forms the seat against which refractory closure member 30 of valve 12 rests.

Opening 45 in plate 15 is closed by an imperforate refractory disc 50 having two opposed. flat faces. Disc 50 is retained between a shoulder in opening 45 and a thin plate 51 bolted to plate 14.

Ordinarily the vessel 10 will have only one teeming opening. However, if it is desired to attach the discharge valve of this invention to a teeming vessel having a pair of discharge openings, the imperforate refractory disc 50 is replaced by a disc such as disc 47 having a central opening therein providing a continuation of the second vessel discharge nozzle.

The valve of this invention is mounted for rotation about its central axis by means of a mounting structure 68 shown in FIGURE 3 which includes a cup-shaped hub 61 having a central opening 62 and a flange 63 at its periphery which supports tray 20. The mounting structure 60 also includes a washer 64, a compression spring 65, a cup-shaped spring retainer 66 having a central opening 67, and an externally threaded screw 68 extending through openings 62 and 6 7 and received in internally screw threaded boss 69 which is stud Welded to the exterior of the vessel 10. This compression spring urges hub 61 toward vessel 10. The flange 63 on hub 61 engages the tray 20 of valve 12 so as to urge the refractory closure member 30 of valve 12 tightly against the refractory insert 47 so as to close tightly the discharge nozzle 11.

It is desirable to cool the mounting structure 60 because of the high heat to which the metal parts thereof are subjected. The cooling structure, which may be seen most easily in FIGURE 7, includes a tube 70, formed in mounting plate 14, through which a forced draft of air may be supplied. This tube 70 may also be seen in FIG- URE 6. As seen most clearly in FIGURE 6, tube 70 extends from the exterior of mounting plate 14 toward opening 46. Air reaching the central opening 46 through tube 70 is diffused over the area, part of it cooling boss 69 and another part entering the space inside hub 61 and in the vicinity of compression spring 65, preventing overheating of the spring.

The actuating means 13 of this invention, seen most clearly in FIGURE 2, includes an hydraulic cylinder 80, having a piston (not shown) therein. This piston has a piston rod 81 extending to the exterior of the cylinder and terminating in a hook-like member '82 which is adapted to engage studs 27 for rotation of valve 12. Conventional means for supplying hydraulic fluid to cylinder 80 may be used. As the piston rod 81 moves outwardly, the hook-like stud-engaging member 82 thereof engages a stud 27 and causes rotation of the valve 12. This rotation successively brings nozzle inserts 32 into and out of alignment with the discharge nozzle 11. Each stroke of the piston in cylinder 80 moves the valve 12 one-half the distance between successive nozzle inserts 32. One stroke moves the valve 12 from the nozzle closing position to a nozzle opening position in which one of the nozzle inserts 32 is aligned with discharge nozzle 11. The next stroke of the piston moves the valve 12 from this nozzle opening position to a nozzle closing position in which an imperforate portion of the refractory closure member 30, approximately midway between successive nozzle inserts 32, covers the bore 48 in refractory insert 47. In the embodiment shown, the discharge valve 12 includes eight teeming openings 23, eight nozzle inserts 32, and sixteen studs 27. Thus sixteen strokes of the piston in cylinder 80 are required to rotate the valve 12 through a complete revolution.

Cylinder 80 is secured to mounting plate 14 by means of a mounting block 85 on which cylinder 80 is pivotally mounted. The block 85 includes an ear 86 which fits between the pair of ears 87 extending from cylinder 80, and a pin '88 secures the two sets of ears 86 and 87 together.

The operation of the discharge valve of this invention is as follows. Assuming that the discharge valve is initially closed, hydraulic actuator 13 is actuated to move piston rod 81 and the stud-engaging member 82 to the extended position, thereby moving valve 12 to a position in which a teeming opening 23 and a nozzle insert 32 are axially aligned with discharge nozzle 11. Actuation can be controlled by a push button on a console remote from the valve actuation device 13. This causes molten steel to be teemed from vessel 10 into a receiving vessel, which is usually an open-ended continuous casting mold. After moving the valve 12, the piston rod is returned to its normal retracted position. Devices known in the art may be used for this purpose. When it is desired to stop teeming steel, the valve 12 is closed by again rotating the valve, so that an imperforate portion of closure member 30 tightly covers the discharge bore 48 of refractory insert 47. All movements of the discharge valve 12 are in the same direction, e.g., clockwise.

This invention provides a discharge valve which is particularly suitable for degassing vessels for molten metal. The discharge valve of this invention provides a fluid-tight closure. Furthermore, the valve may be closed quickly, without any overrun or leakage as the valve is closed. Because of these qualities, the valve of this inven tion provides a discharge closure which is superior to any previously known closures for vessels containing molten met-a1. Although the valve is particularly valuable for degassing vessels, it can also be used to advantage on other types of vessels for containing molten metal, such as ladles and tundishes. This valve is valuable in tundishes because it does provide a tighter and more reliable closure member than the conventional stopper rod and because it enables extended teeming periods without risk of failure of nozzle refractories.

While this invention has been described with references to specific embodiments thereof, it will be understood that the descripution is for purposes of illustration and not for limitation of the scope of the invention.

I claim:

1. Apparatus for teeming molten metal comprising a vessel having a bottom discharge nozzle, a rotatable valve on the exterior of said vessel for controlling the discharge of molten metal through said nozzle, said valve including a refractory disc closure member having at least one teeming opening adapted to be aligned with said discharge nozzle by rotation of said valve, means for mounting said valve for rotation about its central axis, means for maintaining said closure member in contact with the outlet end of said discharge nozzle, and means for rotating said valve, said valve including a circular metal tray hav ing an upturned flange for supporting said closure member, said tray and said closure member having central openings and a plurality of aligned teeming openings, said central openings being adapted to receive said means for mounting said valve, said tray having a plurality of radial ribs and said closure member having grooves for receiving said radial ribs.

2. Apparatus for teeming molten metal comprising a vessel having a bottom discharge nozzle, a rotatable valve on the exterior of said vessel for controlling the discharge of molten metal through said nozzle, said valve including a refractory disc closure member having at least one teeming opening adapted to be aligned with said discharge nozzle by rotation of said valve, means for mounting said valve for rotation about its central axis, means for maintaining said closure member in contact with the outlet end of said discharge nozzle, and means for rotating said valve, said valve including a tray for supporting said closure member, said tray and said closure member having central openings, said means for mounting said valve and for maintaining said closure member in contact with the outlet end of the discharge nozzle including an axially movable hub for supporting said valve, spring means urging said hub and said valve towards the outlet end of said discharge nozzle, and means for preventing lateral movement of said hub and said valve.

3. Apparatus for teeming molten metal comprising a vessel having a bottom discharge nozzle, a rotatable valve on the exterior of said vessel for controlling the discharge of molten metal through said nozzle, said valve including a refractory disc closure member having at least one teeming opening adapted to be aligned with said discharge nozzle by rotation of said valve, means for mounting said valve for rotation about its central axis, means for maintaining said closure member in contact with the outlet end of said discharge nozzle, and means for rotating said valve, said mounting means including a mounting plate attached to the exterior of said vessel, said mounting plate including a refractory insert having an opening for molten metal therein and forming the outlet end of said discharge nozzle, said valve and said means for rotating said valve being mounted on said mounting plate.

References Cited UNITED STATES PATENTS 659,514 10/1900 Dufly 251- 1,105,639 8/1914 Estabrook 251144 1,118,594 11/1914 Spencer 251-304 X 1,214,445 1/1917 Fausek 137-32906 2,880,757 4/1959 Campbell 251-230 X 3,118,472 1/1964 Buie 251-208 X 3,165,795 1/1965 Bahm 251-304 X 3,237,916 3/1966 Bryant 251-58 X 3,344,809 10/1967 Smith 251230 X ARNOLD ROSENTHAL, Primary Examiner.

US. Cl. X.R.

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