US3912134A

US3912134A - Rotary sliding gate valve for molten metal

Info

Publication number: US3912134A
Application number: US465424A
Authority: US
Inventors: Michael Poran
Original assignee: Danieli and C Officine Meccaniche SpA
Current assignee: Danieli and C Officine Meccaniche SpA
Priority date: 1974-04-29
Filing date: 1974-04-29
Publication date: 1975-10-14
Anticipated expiration: 1992-10-14

Abstract

An apparatus for controlling the teeming of molten metal into a mold comprising a valve mounted on a vessel having a bottom discharge nozzle, the valve controlling the discharge of molten metal through the nozzle and discharging the metal along a fixed axis into a mold. The valve includes a rotatable refractory closure member spring loaded across its plane against a seat. The closure member has an inclined channel communicating with the bottom discharge nozzle and with the center axis of the mold so that flow into the mold is along a fixed axis, preferably the longitudinal or center axis of the mold. An actuator mechanism selectively rotates the closure member so that the rate of flow of molten metal from the bottom discharge nozzle into the mold may be varied without altering the flow axis into the mold in relation to the mold axis.

Description

MOLTEN METAL United States Patent 1191 [111 3,912,134

Poran Oct. 14, 1975 ROTARY SLIDING GATE VALVE FOR Primary ExaminerRobert B. Reeves Assistant ExaminerDavid A. Scherbel Attorney, Agent, or FirmFleit & Jacobson [75] Inventor: Michael Poran, Westwood, NJ.

[73] Assignee: Officine Meccaniche Danieli, Udine, [57] ABSTRACT Italy An apparatus for controlling the teeming of molten [22] Filed: Apr. 29, 1974 metal into a mold comprising a valve mounted on a vessel having a bottom discharge nozzle, the valve [21] Appl- N 465,424 controlling the discharge of molten metal through the nozzle and discharging the metal along a fixed axis 52 US. (:1. 222/504; 222/512; 222/555; into a mold- The valve includes a rotatable refractory I 44 closure member spring loaded across its plane against 51 Int. (:1. B22D 37/00 a Seat- T F f member has a inclined Channel 58 Field of Search 222/504, 555, 512; CQmmumcahng t the bottom dlscharge noz'zle and 251/144 with the center ax1s of the mold so that flow into the mold is along a fixed axis, preferably the longitudinal [56] References Cited or center axis of the mold. An actuator mechanism se- UNITED STATES PATENTS lectively rotates the closure member so that the rate of flow of molten metal from the bottom discharge noz- 216 into the mold y b varied without altering the 313233333 Z1973 BZZETJJJJ 242,555 X flow into the mold in relation to the mold 11 Claims, 4 Drawing Figures A /4 I I I9 I y A\ 39 Z /J 94 v 1 A l2 US. Patent Oct. 14, 1975 FIG-l ROTARY SLIDING GATE VALVE FOR MOLTEN METAL BACKGROUND OF THE INVENTION The present invention relates to a bottom pouring vessel for molten metals such as steel and in particular pertains to an improved rotary discharge valve for such vessels so that the teemed metal is always poured along the same flow axis into the mold.

In the past, discharge of molten metal from bottom pouring vessels has been controlled by stopper rods and sliding stopper valves. I

To overcome recognized disadvantages of these prior art discharge mechanisms, various rotary valve assemblies have been developed. The rotary valve assembly is characterized by rotation of the valve member as opposed to reciprocation of a sliding plate. Rotation provides several advantages, such as longer valve use, forward and reverse operation to effect closure and incorporation of multiple valve members in a common disc. One design for such rotary valve was described in an article that appeared in the September, 1973 issue of Iron and Steel Engineer on page 117 entitled Nippon Kokans Rotary Nozzle System for Teeming and Continuous Casing. Another such type of rotary valve assembly is shown and disclosed in U.S. Pat. No. 3,430,644.

While the use of such rotary valves when feeding into a wide receptacle works well, problems occur when feeding into a small mold due to the fact that the metal discharge flow axis shifts laterally as the valve is opened and closed. When producing small billets, less than 8 inches square, such as by use of a water-cooled mold for vertical continuous casting, any lateral shifting of the flow in relation to the mold can and frequently does produce a serious danger of a breakout. As the molten metal flows down and into the water-cooled mold, the metal solidifies first at the mold boundaries thereby forming an outer crust whereas the center remains molten or fluid. The strand comes out of the bottom of the mold and is directed by rollers to a horizontal position and hence to a billet cutting mechanism. If the pour axis into the mold shifts relative to the mold axis, solidification will not occur uniformly and the crust on one side may be so thin that it will break allowing the molten metal in the interior to breakout or washout after having exited from the bottom of the mold. It is known in the industry what a mess this can be and how expensive and time consuming it is to clean up.

The object of the present invention is to provide a novel rotary valve which avoids lateral shifting of the molten flow relative to the mold axis and thereby substantially lessens the problem of breakout, washout and the like. Furthermore the arrangement of the inventive valve is carried out in a unique and novel way to enable quick exchange of the valve or valve components.

SUMMARY OF THE INVENTION The present invention comprises a rotary type discharge valve for mounting on a tundish bottom for rate of flow variation as well as opening and closing the discharge nozzle of the tundish without laterally shifting the outlet flow relative to the water-cooled receiving mold. The valve element is comprises of a refractory disc, spring loaded across its plane, having an inclined bore which is brought into alignment with the tundish discharge nozzle, and is activated for opening and closing by a hydraulic piston. The discharge valve, because of its unique arrangement, is easy to maintain and repair and is capable of repeated opening and closing in rapid sequence without dribbling or leaking molten metal. Metal discharged through the valve due to its unique and novel organization is always discharged along a fixed axis preferably aligned with the center or longitudinal axis of the mold.

Other features and advantages of the invention will be apparent from the following description of the preferred embodiment of the invention as shown in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic representation of a general arrangement for pouring steel;

FIG. 2 is a cross section of the mold of FIG. 1 taken along lines 2 2;

FIG. 3 is an enlarged cross sectional view of the novel rotary discharge valve mounted on the bottom of a tundish; and

FIG. 4 is a bottom plan view of the rotary valve shown in FIG. 3 with the heat shield removed.

DETAILED DESCRIPTION OF THE DRAWINGS In the drawings, tundish 11, containing molten steel or other molten metal receives its charge from ladle l0 and discharges through valve 12 into mold 13. The cast metal is designated by reference letter M and is turned by rollers R to a horizontal position from which it is fed to a billet cutting mechanism not shown. The vessel shown is a tundish; however a ladle, vacuum degassing vessel or any other vessel which may be suitably used for teeming molten steel can be used.

Referring to FIG. 3, tundish ll conventionally has a refractory lining 14, an outer metallic shell 16 and a tundish discharge nozzle 18 for discharging metal from the bottom. The discharge nozzle 18 is opened and closed by the rotary valve 12 which rotates about a central axis AA. The rotary valve 12 of the invention basically comprises four components, namely, a base assembly 20 secured to the tundish, a valve support assembly 22 secured to the base assembly 20, a rotary closure assembly 24 rotatably mounted in the valve support assembly 22 to control discharge from the tundish discharge nozzle 18 and a drive mechanism 26 to rotate the rotary closure assembly 24.

The base assembly 20 of the valve 12 is comprised of a mounting plate 30 which is welded or otherwise secured to the metal shell 16 of tundish 11, an annular metal support member 42 secured to the mounting plate 30 and a refractory subassembly consisting of a metal ring 31 cemented to the periphery of a refractory disc 33 defining a bore 32. Three equally spaced throughgoing threaded bores 34 are defined in the mounting plate 30, in axial alignment with bores 35 defined in annular member 42 and threaded bores 17 in the outer shell 16. The base assembly 20 is attached to and carried by the tundish l l by means of studs 37 and nuts 36.

The ring member 31 profiled with a complementary shoulder seats against a shoulder 43 formed in the annular support member 42 and is held in place by screws 74. The circular refractory disc 33 and ring member 31 are also profiled with complementary shoulders and are secured together by cement or other suitable means so that the disc and retaining member are rigidly fixed together and constitute a unitary member. The throughgoing bore 32 of disc 33 is coaxially aligned with the bore 19 of tundish nozzle 18 to allow the molten metal to pass therethrough.

The annular support member 42 also defines a plurality of equidistantly spaced spring member support bores 39, each of which is constructed to receive and hold a spring subassembly 60 for mounting the valve support assembly 22 on the base assembly 20. Each spring subassembly 60 of the valve support assembly 22 is held in position by means of a set screw 65 seated in a stepped bore 64 so that the set screw 65 can engage and hold the spring subassembly 60 in place.

The valve support assembly 22 comprises an annular body 55 defining a shoulder 56 for rotatably supporting the closure assembly 24 and a plurality of bores 57. Located within each bore 57 is a sleeve 58 terminating in a bottom flange 59.

Each spring subassembly 60 consists of a guidepin 62, a bolt 63 secured to the lower end of guidepin 62, and a disc spring assembly 67 mounted between the head of bolt 63 and a retaining ring 68.

A spring seat 69 in the form of a cup shaped member acts as a spring heat shield and is mounted against the head of the bolt 63 to seat one end of the spring 67. The other end of spring 67 bears against the flanged end 59 of sleeve 58 received in bore 57 formed in the annular body 55. The flange 59 bears against shoulder 66 of the annular body 55. Guidepin 62 is also received in sleeve 58 so that the floating support valve assembly 22 is movably supported from the base assembly 20 by means of the spring subassemblies 60. The spring subassemblies 60 act to spring load the closure assembly 24 uniformly across its plane against disc 33 in fluid tight engagement so that a uniform load can be maintained when the steel and refractory components are heated and the steel is being poured.

The rotary closure assembly 24 is rotatably mounted in the floating support assembly 22. The rotary closure assembly 24 comprises a ring holder 38 mounted on the shoulder 56 of annular body 55, a disc shaped refractory plate 40 defining a bore 45 cemented to the ring holder 38 like ring 31 and disc 33 and a collector nozzle subassembly. The refractory plate 40 and the holder 38 cemented thereto function as a single closure member. The refractory plate 40 has an angled or inclined teeming bore 42 extending through it which communicates with and is aligned with bore 32 of disc 33 when the closure assembly 24 is in the fully open teeming position. The teeming bore 42 is preferably of a slightly smaller or the same diameter as the communicating base assembly disc bore 32. The throughgoing angled teeming bore 42 is preferably cut through the refractory plate 40 at a 40 angle from vertical. The rotary refractory plate 40 abuts against and is adapted to rotate against the surface of disc 33 when the closure assembly is rotated by valve drive mechanism 26.

The rotary refractory plate 40 is preferably composed of high-alumina material made from crystalline alumina containing about 80 to 90 percent A1 or, if desired of zirconia composition. However, other refractory material having a high resistance to corrosion and erosion resulting from molten metal and slag is known in the art and may be chosen.

The ring shaped refractory holder 38 defines a plurality of threaded bores 44 to receive screws 46 in threaded engagement to secure a collector nozzle holder member 48 in a fixed relationship to the refractory holder 38. The nozzle holder 48 defines a shoulder 49 on which a collector nozzle 50 is seated by means of shoulder 70. The collector nozzle 50 has a throughgoing teeming bore 52 which communicates with and is always aligned with the lower end of inclined teeming bore 42 of rotary refractory plate 40. The axis of teeming bore 52 forms the central axis of the rotary valve. The length of the collector nozzle 50 is suitably selected and the bore 52 is suitably tapered so that the metal exiting from the bore smoothly flows into the center of mold 13 where it will cool uniformly. in additin to the support afforded by holder 48, the collector nozzle 50 is preferably secured by a suitable cement to the rotary refractory plate 40 in a recess 41 formed in the rotary refractory plate 40 to form a liquid tight seal. When the rotary closure assembly 24 is rotated, the collector nozzle 50 rotates with it around the center axis A-A of the valve and thus the metal is always poured into the mold along a fixed axis irrespective of the rate of flow or the degree of opening of the valve.

An actuator slot or seat 74 is cut in the refractory holder 38 to receive and hold the end of swing arm 76 of the drive mechanism 26.

The drive mechanism 26 comprises a swing arm 76 having at one end a disc 82 spaced from arm 76 by stud shaft 83. The other end of arm 76 connected to pivoting linkage 86 is connected to the piston rod of the hydraulic cylinder 90 which is trunnion mounted to the support member 89 mounted to the base support assembly 20 which if desired can be provided with quick disconnect means allowing it to be easily disconnected from the base plate support member 42. The linkage 86 connects with a piston rod 88 of a hydraulic cylinder 90 so that when the piston in the cylinder is activated the cylinder rod pushes the swing arm approximately 60 or any desired amount to open and close the valve. Since this hydraulic arrangement is well known in the art, no specific elaboration of its description is felt necessary.

If desired a heat shield 91 can be used with the valve 12. The heat shield 91 is suspended from the floating support assembly 22 by suitable securing means. The heat shield comprises a planar shield member 92 having a central aperture 94 cut therein which allows the collector nozzle 50 to project therethrough. A circular tube section 96 is secured to the planar surface by welding to form a protective sleeve for the spring assemblies. Screws 98 secure the heat shield to body of the floating support assembly.

The operation of the rotary discharge valve 12 of the invention is as follows. Assuming that the discharge valve is initially closed, the drive mechanism 26 is actuated to rotate the rotary closure plate 40 over the surface of the stationary disc 33 so that the rotary closure plate bore 42 communicates with the teeming bore 32 of the stationary disc 33 and tundish nozzle bore 19. The collector nozzle 50 is always aligned with the lower end of plate bore 42 and because nozzle 50 rotates with the closure member plate 40, molten metal flows from the tundish into the tapered bore 52 of the collector nozzle and always exits along central axis AA into the mold. Since the central axis of the valve passes through the center of the bore 52, rotation of the closure member does not affect the directional flow of metal from the valve into the mold.

Actuation of the drive mechanism 26 can be controlled by a push button on a console remote from the valve activation device which will causemolte'n steel to be teemed from the vessel into a receiving vessel which is usually an open ended continuous casting mold, or it can be automatically and proportionally controlled by an electric signal from a mold level control system.

When it is desired to stop teeming steel, the valve 12 is closed by again rotating closure plate 40 so that a portion of the rotary plate 40 tightly covers the discharge bore 32 of the disc 33 stopping flow of the molten metal. The movements of the discharge valve can be in a clockwise or counter clockwise direction.

While the invention has been described with reference to specific embodiments thereof, it is understood that the description is for purposes of illustration and not for the limitation of the scope of the invention.

What is claimed is:

1. The combination of a vessel having a discharge port for dispensing molten metal and a rotary valve mechanism for controlling the flow of molten metal teemed from the discharge port of said vessel, said rotary valve mechanism comprising a base means mounted on said vessel adjacent its discharge port, said base means defining a first throughgoing teeming bore therein adapted to be in communication with the discharge port, a support member connected to said base means, rotatable closure means defining a second throughgoing teeming bore adapted to be placed into and out of communication with said first throughgoing teeming bore rotatably mounted in said support member, a nozzle means secured to said rotatable closure means, said nozzle means defining a third throughgoing teeming bore axially aligned with the central axis of the valve mechanism and communicating with the second throughgoing teeming bore, the end of said second through-going teeming bore communicating with said third throughgoing teeming bore being axially aligned with the central axis of the valve mechanism and the other end of said second throughgoing teeming bore adapted to communicate with said first throughgoing teeming bore being laterally offset from the central axis of the valve mechanism, and actuator means connected to rotate said rotatable closure means against said base means so that said second throughgoing teeming bore can be placed into and out of communication with said first throughgoing teeming bore, or in any position between these extremes without changing the axis of the outflowing metal from the third throughgoing teeming bore.

2. A valve mechanism as claimed in claim 1 including a heat shield secured to said support member to protect said valve mechanism from the heat of the molten metal teemed from said nozzle means.

3. A valve mechanism as claimed in claim 1 wherein said support member defines a stepped chamber adapted to hold said rotatable closure means and a plurality of spring means chambers, spring means positioned in each spring means chamber connecting said support member to said base means.

4. A valve mechanism as claimed in claim 3 wherein each spring means comprises a guide pin adapted to be inserted in said base means and said support member spring means chamber, said guide pin including retaining means, a spring holding means secured to said pin, a spring member mounted around said spring holding means with one end of said spring member abutting against a sleeve member mounted in said spring means chamber and the other end abutting against a spring seat mounted to said spring holding means.

5. A valve mechanism as claimed in claim 3 wherein said plurality of spring means chambers comprise at least three spring means chambers uniformly spaced in said support member.

6. A valve mechanism as claimed in claim 1 wherein said base means comprises a base member defining actuator support means, a plurality of spring means chambers and a stepped chamber, a refractory subassembly secured in said stepped chamber, said refractory subassembly comprising a retaining member secured to said base member in said stepped chamber and a disc member secured to said retaining member, said disc member defining said first throughgoing teeming bore.

7. A valve mechanism as claimed in claim 1 wherein said rotatable closure means comprises a second refractory subassembly, said second refractory subassembly comprising a retaining member rotatably mounted in said support member and a disc member secure to said retaining member.

8. A valve mechanism as claimed in claim 7 wherein said closure means throughgoing teeming bore is inclined with respect to the valve mechanism central axis.

9. A valve mechanism as claimed in claim 1 wherein said noule means throughgoing bore is tapered.

10. Apparatus for teeming molten metal into the central axis of a mold comprising in combination a vessel having a bottom discharge nozzle, and a rotatable valve mechanism mounted to the exterior of said vessel adjacent the bottom discharge nozzle for controlling the rate of discharge of molten metal through said discharge nozzle, said valve member comprising a stationary base means connected to said vessel, said stationary base means comprising a base member defining a stepped chamber, a first subassembly fixedly mounted in said stepped chamber, said first subassembly comprising a retaining member secured to said base member and a refractory plate secured to said retaining member, said refractory plate defining a teeming bore axially aligned with said vessel discharge nozzle, spring means movable connecting a floating support means to said base means, said spring means comprising at least three spring members connected to and uniformly spaced on said floating support means and said base means, said floating support means comprising a body member defining a stepped chamber, a second subassembly comprising rotatable closure means slidably mounted in said body member chamber, said closure means comprising a second retaining member, and a second refractory plate secured to said second retaining member, said second refractory plate defining a second inclined teeming bore, said closure means being rotatably mounted in said floating support means and biased by said spring means across its plane against said first refractory plate, with said second teeming bore being adapted to be selectively aligned with said first refractory plate teeming bore through rotation of said closure means, a nozzle holding member secured to said second retaining member and a nozzle mounted to said nozzle holding member, said nozzle having a bore axially aligned with thecentral axis of said valve member and communicating with said second refractory member teeming bore and rotating means mounted to said second retaining member, said rotating means comprising a hydraulic cylinder connected by linkage 11. Apparatus as claimed in claim 10 wherein said closure means teeming bore is angled with respect to the axis of said first refractory plate teeming bore, and

communicating with the third teeming bore.

Claims

9. A valve mechanism as claimed in claim 1 wherein said nozzle means throughgoing bore is tapered.

10. Apparatus for teeming molten metal into the central axis of a mold comprising in combination a vessel having a bottom discharge nozzle, and a rotatable valve mechanism mounted to the exterior of said vessel adjacent the bottom discharge nozzle for controlling the rate of discharge of molten metal through said discharge nozzLe, said valve member comprising a stationary base means connected to said vessel, said stationary base means comprising a base member defining a stepped chamber, a first subassembly fixedly mounted in said stepped chamber, said first subassembly comprising a retaining member secured to said base member and a refractory plate secured to said retaining member, said refractory plate defining a teeming bore axially aligned with said vessel discharge nozzle, spring means movable connecting a floating support means to said base means, said spring means comprising at least three spring members connected to and uniformly spaced on said floating support means and said base means, said floating support means comprising a body member defining a stepped chamber, a second subassembly comprising rotatable closure means slidably mounted in said body member chamber, said closure means comprising a second retaining member, and a second refractory plate secured to said second retaining member, said second refractory plate defining a second inclined teeming bore, said closure means being rotatably mounted in said floating support means and biased by said spring means across its plane against said first refractory plate, with said second teeming bore being adapted to be selectively aligned with said first refractory plate teeming bore through rotation of said closure means, a nozzle holding member secured to said second retaining member and a nozzle mounted to said nozzle holding member, said nozzle having a bore axially aligned with the central axis of said valve member and communicating with said second refractory member teeming bore and rotating means mounted to said second retaining member, said rotating means comprising a hydraulic cylinder connected by linkage to said retaining member to drive said closure means and nozzle in a rotating direction to bring said closure means refractory plate teeming bore into and out of communication with the first subassembly teeming bore.

11. Apparatus as claimed in claim 10 wherein said closure means teeming bore is angled with respect to the axis of said first refractory plate teeming bore, and communicating with the third teeming bore.