Sliding gate valve for teeming molten metal

Abstract: A sliding gate valve (5) has a frame with a sliding carrier (11) within the frame, a stationary plate secured at an upper portion of the valve and a slide gate plate (16) secured at a lower portion of the valve. In one embodiment a spring plate (12) is provided with beam springs mounted in cantilever fashion with their end portions orientated in surrounding relationship to a teeming opening of the valve. In addition, a cluster (28) of such springs is provided at a shut-off portion of the slide plate which underlies the teeming opening to the vessel in the shut-off position. This mounting may be reversed with the springs secured in cantilever fashion to the carrier and the spring plate eliminated, while the springs bear directly on the underside of the metal encased refractories (19). The spring plate can have the cantilever springs mounted on both sides and is positioned between the slide gate plate and the carrier. This results cutting the spring rate in half. By providing double springing, such as reversely folding a pair of springs upon each other, also cuts the spring rate in half. With spring pairs mounted on each other on one side of the spring plate and a single spring on the other side, the spring rate is cut to one-third of that of a single spring. To cut the spring rate to one fourth, doubled springs are used on both faces of the spring plate.

Description: The present invention relates to a sliding gate valve commonly used in the teeming of molten metal such as steel. More specifically, it relates to a sliding gate reciprocating valve having two or more opposed sliding plates such as disclosed in US-A-4,063,668. US-A-4,063,668 discloses a sliding gate reciprocating valve having a plurality of pressure pads activated by coil springs which engage a slide gate in a carrier which slide gate, in turn, engages a stationary plate. The two plates each have a teeming orifice which is moved in and out of alignment to control the flow of steel from a vessel to which the valve is mounted. A three plate sliding gate valve is also disclosed. Additionally, the prior art discloses bandless refractories for use in such type valve as appearing in US-A-4,573,616 and 4,582,232. Finally, US-A-4,561,573, discloses the use of a pressure plate positioned underneath the slide gate in order more uniformly to transfer the loads from the discrete pressure points applied by the coil spring pads of US-A-4,063,668. A distinct problem may arise with the negligent use of the valve such as shown in US-A-4,063,668, since the coil springs cannot operate satisfactorily at temperatures exceeding 800°F (427°C). Indeed, it is most desirable that the temperature not exceed 400°F to 600°F (204° - 316°C). This is a peculiar property of coil springs as set forth in US-A-5,062,553. There it was recognised that certain forms of tool steel can be used when a cantilever spring is employed. Such steels can withstand temperatures of up to 1100°F (593°C) and still endure fatigue and flex within the elastic limits for hundreds of thousands of deflections. A coil spring is shown in the environment of a typical tundish valve in US-A-4,415,103. Such springs are, however, linearly mounted and apply, for the tundish valve environment, the necessary pressure to hold the two sequential refractory plates in pressure face-to-face and leak-proof contact. However, as is well known in the art, when the ferrostatic pressure of a ladle gate valve is encountered which is many times the ferrostatic pressure of a sequential tundish valve, leakage can occur. This problem was addressed and contained by following the structure and method as shown in US-A-4,063,668. Nonetheless, despite all of the technology as set forth in the prior art above, the structure shown in US-A-4,063,668 is vulnerable to the negligent loss of cooling air. In more than one instance where the cooling air was negligently taken off the valve and the ladle set aside with a charge of molten metal, the springs of the valve elevated to a temperature where leakage occurred. It follows that it is desirable to develop a valve in which no cooling air is required and the safety factor for excessive heat on the springs is readily accommodated by ambient air. In addition, it is desirable to develop such a valve in which a bandless refractory such as in US-A-4,573,616 and 4,582,232 can be employed. The clamping rings and the force components exerted eliminate the necessity for mounting refractory in a mortar and a container. This overcomes irregularities and manufacturing problems which result from a metal encased refractory not having two parallel planar faces. Coil springs have been omitted in favour of a single Belleville spring around the collector as shown in US-A-4,358,034. Also a spring toggle slide gate valve is shown in US-A-4,199,085. Such a spring does not address surface irregularities remote from the teeming orifice. In view of the foregoing, it becomes apparent that what is needed is a valve in which the springs do not require air cooling, in which the load of the springs is uniformly distributed to the refractory, and in which the refractory may be of the bandless highly secured type, and in which a pressure plate is optionally employed which will uniformly distribute the force of the springs over the refractory thereby to cause a good face-to-face sealed relationship between the stationary plate or plates and the slide gate or sliding plate. In addition, the valve should desirably have means for self engagement with the stationary plate which, as the slide plate, is also bandless in nature and has the two component force securing the same to the valve. Also, it is desirable to reduce the spring rate in any such valve thereby to increase the amount of deflection for a given load and accommodate additional temperature variations, structural deflection, or dimensional inaccuracies. According to one aspect of the present invention, there is provided a sliding gate valve for a vessel containing molten metal including a mounting plate, means for securing the mounting plate to the vessel, a teeming orifice the valve having a top plate loaded against the mounting plate, a frame, a carrier for reciprocation in the frame, and a metal-encased sliding plate with metal teeming means, characterized in that a plurality of springs are secured in cantilever fashion to the carrier with pressure points extending from the carrier in surrounding relationship to the metal teeming means of the sliding gate plate, and offset springs on one portion of the carrier. According to a second aspect of the present invention, there is provided a spring plate for use with a sliding gate valve, the valve having a reciprocating slide gate plate, a stationary plate and a carrier for securing the reciprocating gate plate in face-to-face relationship with the stationary plate and the spring plate being positioned between the carrier and the slide plate, characterized in that a plurality of yieldable cantilever springs are secured to one face of the spring plate. In a particular embodiment of the present invention, the sliding gate valve has an upper stationary plate, a lower stationary plate and a reciprocating intermediate plate, each said plate having a teeming orifice therein, and a means for securing the three plates in face-to-face relationship, with the springs being located to the inside of the means for securing the three plates and positioned to engage the stationary plate of the three plates, which is lowermost when assembled. The present apparatus is generally directed to a sliding gate valve having a frame, a sliding carrier within the frame, means for securing the carrier in reciprocating relationship to the frame, a stationary plate secured at the upper portion of the valve, and a slide gate secured at the lower portion of the valve. In one embodiment a spring plate is provided with beam springs cantilever mounted on its underside having their end portions orientated in surrounding relationship to the teeming opening of the valve, and in addition, providing a cluster of such springs at the shut-off portion of the slide gate which underlies the teeming opening to the vessel in the shut-off position. This mounting may be reversed with the springs secured in cantilever fashion to the carrier and the spring plate eliminated while the springs bear directly on the underside of the metal encased refractories. All of the springs are fixedly mounted for applying in cantilever fashion a yieldable load. As to the spring plate, the springs extend downwardly to engage a spring pressure raceway ring formed in the interior portion of the carrier throughout its length and width and partially surrounding the teeming opening of the valve. In addition, a spider-like cluster of springs is provided underneath the shut-off portion to load it when in the shut-off position. In yet another embodiment, a spring plate having springs mounted in cantilever fashion on both sides is positioned between the slide gate and the carrier. This results cutting the spring rate in half. Other embodiments with double springing such as reversely folding a pair of said springs upon each other also cut the spring rate in half. Yet another embodiment with spring pairs mounted on each other on one side of the spring plate and a single spring on the other side cuts the spring rate to one-third of that of a single spring. To cut the spring rate to one fourth, doubled springs are used on both faces of the spring plate. The method comprises positioning beam springs in a valve environment to the end that they surround the teeming opening in close proximate relation thereto, and have an auxiliary positioning of a cluster of springs to underlie a shut-off portion of the plate. In addition, the valve relates to the utilisation of a bobtailed-type spring plate which is not bilaterally symmetrical in conjunction with a refractory plate in the sliding gate portion of a sliding gate valve. Thus in the sliding gate valve, the springs can operate without being cooled by an independent pressure air source. Further, bending beam springs can be employed in conjunction with a spring plate which, in addition to exerting pressure uniformly on the sliding refractory, also serves to couple a collector nozzle in place beneath the pressure plate. The spring plate can be provided with associated springs which cuts the spring rate in half, thereby doubling the deflection required to impose a given load. This imparts additional flexibility to the entire assembly of the valve. By forming the spring plate with an interior thickened section, it resists the bending moment of the beam springs positioned at its exterior as well as offsets the inherent sag occurring in the spring plate as a result of elevated temperatures, particularly where the spring plate is in close proximity to the teeming orifice of the valve. A valve construction with significantly improved spring support means permits the steel maker to readily withdraw and service and inspect each and every spring plate at each and every replacement of the refractory and the return of the same to service. There is also the advantage of the utilisation of cantilever springs in a sliding gate valve, since the cantilever spring metal construction is not of an exotic variety, is readily obtainable, and thereby reduces the cost in addition to augmenting the life of such springs. The present invention also includes within its scope a method of teeming molten metal from a vessel containing molten metal through a sliding gate valve secured to the vessel by means of a mounting plate, wherein the sliding gate valve is a sliding gate valve of the present invention. For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:- Figure 1 is a perspective view of one form of valve opened to show a star spring type construction; Figure 2 is a view of a second form utilising a spring plate in which beam springs are employed; Figure 3 is a plan view of a carrier of the valve with a pressure plate and refractory removed; Figure 4 is a longitudinal section illustrating cantilever springs taken along line 4-4 of Figure 3; Figure 5 is a view of the orientation of the cantilever springs shown in Figure 3 taken along section line 5-5 of Figure 3; Figure 6 is a plan view of an underneath portion of the spring plate; Figure 7 is a longitudinal sectional view of the spring plate and springs taken along line 7-7 of Figure 6; Figure 8 is a further longitudinal sectional view of Figure 7, but showing the environment of the sliding plate and a depending nozzle in conjunction with the spring plate and, in addition, the clamping mechanism for the slide plate portion; Figure 9 is a plan view of another form of spring plate; Figure 10 is a transverse sectional partly broken-away view of the spring plate shown in Figure 9; Figure 11 is another transverse sectional view of the spring plate shown in Figures 9 and 10 but in its compressed relationship with a sliding gate; Figure 12 shows another form of spring plate with different types of springs; Figure 13 is a transverse sectional view of the form of spring plate shown in Figure 12 taken along line 13-13 of Figure 12; Figure 14 shows another form in which the spring plate is utilised with a bandless refractory and double springing is involved between the springs on the lower portion of the spring plate and the upper portion of the carrier; Figure 15 is a transverse sectional view of the double spring plate of Figure 12 taken along line 15-15 thereof; Figure 16 is a transverse sectional view of the double spring plate of Figure 12 taken along line 15-15 thereof but actually showing one additional set of springs on top of the spring plate and abutting an encased refractory member; Figure 17 is a plan view of another form in which the leaf springs are double sprung on the underneath side portion of the spring plate; Figure 18 is a sectional view taken along line 18-18 of Figure 17, showing the double spring springs on the underneath portion of the spring plate so that the spring plate can engage a bandless refractory; Figure 19 is taken along line 19-19 of Figure 17 and shows the bandless refractory member in place with the double spring assembly beneath the spring plate; and Figure 20 is yet another embodiment in which both a spring plate and a pressure plate are employed. An example of the present valve 5 is shown in Figure 1. There, it will be seen that the basic members include a vessel wall 6 to which the valve 5 is secured in surrounding relationship to a well nozzle 8. A carrier 11 is provided in order to receive a slide gate plate 16 and its collector nozzle 17. Subsequently a heat shield 25 is secured to the underneath portion of the carrier 11. A star spring 22 has a heel ring 23 (shown also in Figure 3). Provision is also made for a three leaf spring 28 having a cantilever portion 48 which engages the under portion of the slide plate 16. In another embodiment, shown in Figure 2, the valve is provided with a spring plate 12 having an associated clamp ring 13 (Figure 8). Beam springs 27 are individually secured to the spring plate 12 by means of respective mounting bolts 55. A slide plate 19 is uncanned or unbanded as is also a replaceable collector nozzle 18. Figure 3 shows in greater detail that the carrier 11 supports the heel ring 23, from which the star springs 22 extend inwardly and upwardly. The heel ring 23 is secured to the carrier by means of bolts 55. A clamp 80 provides the vehicle for this securement. The cantilever portion 48 of each spring 22 extends inwardly to a working face 65 which, in turn, abuts the underneath portion of the slide gate 16. The three leaf spring assembly 28 is shown in the left-hand portions of Figures 3 and 4 and is also secured to the carrier 11 by means of one of the mounting bolts 55. Similar reference numerals have been employed for the cantilever portion 48 and the working face 65. Figure 5 illustrates the mounted relationship between the slide plate 16 and both the star springs 22 and the three leaf spring 28. The star spring 22 is in surrounding relationship to the collector nozzle. The embodiment of a spring plate shown in Figures 2 and 8 is also shown in Figure 6. There can be seen the beam springs 27, each of which is secured by means of the bolt 55 at its mid-portion so that the extending ends all extend downwardly. Instead of a star spring 22, springs in the form of cantilever springs 26 having the cantilever portions 48 are secured by the mounting bolts 55 to the spring plate 12. Figure 7 shows how the individual springs 26 are secured to the spring plate 12. In the foregoing embodiments the spring plate 12 may be made thicker in its central portion surrounding the collector nozzle, thereby to reduce plate deflection. Figure 8 shows the uncanned-unbanded refractory plate 19 and associated collector nozzle 18, which is held in place by means of a threaded dependency 29 as it is secured to the upper portion of the nozzle holder 14. The clamp ring 13 is then secured by means of bolts 10 to the spring plate 12. A further modification to the embodiment just described results from the elimination of the spring plate 12, and instead securing the springs as shown in Figure 6 directly to the upper portion of the carrier. The springs bear directly against the underneath portion of the metal encased sliding gate refractory as shown in Figures 1 and 5. In short, the individual springs of the second embodiment as illustrated in Figure 6 with the spring plate 12 can be substituted as an alternative for the ring and spider-like construction shown in Figure 3. In the modification of the spring plate 12 shown in Figure 9, a star spring 22 version is shown where the star springs 22 extend internally of a heel ring 23. The heel ring 23 is secured by means of the clamp 80 and mounting bolts 55. As shown, the working face 65 of the star springs 22 engage in cantilever fashion the underneath portion of the slide plate. To underlie the plate in the shut-off position, a further three-leaf spring 28 is offset from the star springs 22 and secured by means of mounting bolts 55 at the heel portion 46 of the cantilever portion 48 of the springs which terminate in a working face 65. The same are all shown in transverse view in Figure 10, where it becomes apparent that the plurality of springs, each opposing the spring plate 12 in mirror image, provide for a one-half spring rate and double deflection. Figure 11 is another view of the spring plate 12 as shown in Figures 9 and 10 but taken along section line 11-11 of Figure 9 and showing the same in its compressed relationship to the slide gate plate 16 and the carrier 11 of the valve assembly 5. In the embodiment of spring plate 12 shown in Figures 12, 13 and 15, which is distinguishable from that shown in Figures 9, 10 and 11, individual double working face springs 27 are employed instead of the star springs. Similarly, instead of the spider-like spring underneath the shut-off portion, a plurality of cantilever springs 26 having a cantilever portion 48 secured to a heel portion 46 are mounted by bolts 55. The double leaf presentation is best illustrated in Figure 13 and shown in its host environment in Figure 15 where the spring plate 12 and its springs engage the sliding gate 16 of the valve 5 and is sandwiched therebetween and the carrier 11. The embodiment of spring plate 12 shown in Figure 14 serves to mount the clamp ring 13 when employed with an uncanned slide gate 19. The replaceable collector nozzle 18 is secured in place by means of the nozzle holder 14 through its threaded upper end portion. Figure 16 shows the first embodiment of a modified double leaf spring where the underneath portion of the spring plate 12 has its cantilever springs mounted to engage comparable springs on the carrier. Additional springs are mounted with the cantilever portion 48 secured by means of the mounting bolt 55 with a working face 65 extending upwardly to engage the lower encased portion of the slide gate plate 16. With the concept of double springing, this can be accomplished as shown in Figures 17 and 18 where a double spring assembly 70 is formed by securing two cantilever springs 26 with a mounting leaf and connecting leaf 71, 72 secured by means of a doubler fastener 75. Actually, the central double spring 70 has a double beam portion 76 secured by means of mounting bolt 55 to the spring plate 12. Figure 19 discloses an embodiment in which the spring plate 12 secures the clamp ring 13 in place to engage the uncanned slide gate 19. Necessarily with the uncanned refractory 19 the upwardly extending springs as shown in Figure 16 are omitted in favour of the double spring assembly 70 beneath the spring plate 12. Figure 20 shows an embodiment in which the spring plate 12 has springs on both sides and is combined with a pressure plate 35. The pressure plate 35 serves to distribute the load of the springs on the spring plate 12 over the face of the refractory, and also to secure the bandless refractory to the pressure plate by means of the clamp ring 13. The spring rate of the system becomes that of the spring plate of Figures 9-15 which is one-half of the normal since the spring plate 12 of Figure 20 has springs on both the upper and the lower face. The materials employed for the beam springs just described are generally known as high speed tool steel. They possess high strength and heat resistance, and are relatively inexpensive. Such materials substitute for the rather exotic type materials employed with the coil springs. Actual tests have shown that the coil springs which are replaced by this invention are designed to operate below 900°F (482.2°C) and are of rather expensive exotic metals such as maragin steels. The machinable steel as employed with the springs disclosed herein can operate at temperatures up to 1200°F (648.8°C). In an actual test report a block of steel comparable to the cantilever spring disclosed, but in a totally different environment and configuration, will flex over five hundred thousand times at a temperature of 1000°F (537.7°C) or more. The advantages which flow from reducing the spring rate are significant. If one assumes that the range of sealing force from minimum to maximum for any one size refractory set, size being based upon surface area, is fixed and must be maintained; if the spring rate of the system is cut in half, then the dimensional stack-up variation tolerance of the system is doubled. If one assumes, for example, that the allowable force range for a valve system is 5000 kgf to 7000 kgf (49035 to 68649 N) and the spring rate is 2000 kgf per millimetre (19614 N/mm), the total allowable stack-up variation tolerance including refractory tolerance and mechanical tolerance range combined is 1 mm or +/- 0.5 mm from nominal. A double spring application of the same components reduces the rate to 1000 kgf per millimetre (9807 N/mm) and makes the stack-up variance tolerance 2 mm or +/- 1 mm from nominal. A triple stack spring with the same components results in an effective rate of 667 kgf per millimetre (6541.27 N/mm) and allows a +/- 1.5 mm variation. The greater the stack-up variation tolerance a system will accommodate, the more forgiving the system is of refractory manufacturing tolerances, the chemical manufacturing tolerances, and mistakes made in "making up" the system for service. Larger allowable manufacturing tolerances tend to relate to lower costs. Conversely stated, as manufacturing tolerances approach zero defect, the cost of production increases significantly. The more forgiving a system is of mistakes in setting it up for use, the fewer operating problems it will have. A lower spring rate may allow, but does not force, a system to be able to use remanufactured plates. Finally, when the spring rate of the system is cut in half, or more, the effects of thermal expansion and distortion are also cut in half, or more. It will be appreciated that the need for outside air to cool the springs is no longer required. Further, the springs transfer a load proportional to the sealing of the valve to the interface between the stationary plate and the slide plate.

Claims: A sliding gate valve (5) for a vessel containing molten metal including a mounting plate, means for securing the mounting plate to the vessel, a teeming orifice (8), the valve having a top plate loaded against the mounting plate, a frame, a carrier for reciprocation in the frame, and a metal-encased sliding gate plate (16) with metal teeming means, characterized in that a plurality of springs (22) are secured in cantilever fashion to the carrier (11) with pressure points extending from the carrier in surrounding relationship to the metal teeming means of the sliding gate plate, and offset springs (28) on one portion of the carrier. A sliding gate valve as claimed in claim 1 wherein the metal teeming means comprises a collector nozzle (17) depending from the sliding gate plate for insertion in the carrier and the springs (22, 28) beat directly in cantilever fashion on one face of the slide gate plate (16) when assembled. A sliding gate valve as claimed in claim 1 wherein the metal teeming means is a teeming opening in the sliding gate plate, there being a pressure plate for load distribution and attachment of a collector nozzle and the springs bear directly on an underneath portion of the pressure plate. A sliding gate valve as claimed in any one of the preceding claims, wherein each spring comprises a simple beam formed or machined form a high strength heat resistant metal and having a cantilever load resistance flexing portion (48), a load application portion (65) and a means (55) for affixing the spring at the end (80) of the load resistance portion remote from the load application portion. A sliding gate valve as claimed in claim 4, wherein each spring is a multi-leaf cantilever spring. A sliding gate valve as claimed in claim 6, wherein each spring is a ring form star spring (22) with independent cantilever fingers (65). A sliding gate valve as claimed in claim 6, wherein the fingers of the star spring are joined at the end to a heel ring (80) surrounding the teeming orifice. A sliding gate valve as claimed in claim 6, wherein each spring is a single leaf spring. A sliding gate valve as claimed in claim 1 having an upper stationary plate, a lower stationary plate and a reciprocating intermediate plate, each said plate having a teeming orifice therein, and means for securing the three plates in face-to-face relationship, wherein the springs (22) are located to the inside of the means for securing the three plates and positioned to engage the stationary plate of said three plates, which is lowermost when assembled. A spring plate (12) for use with a sliding gate valve, the valve having a reciprocating slide gate plate, a stationary plate and a carrier (11) for securing the reciprocating gate plate in face-to-face relationship with the stationary plate and the spring plate being positioned between the carrier and the slide plate, characterized in that a plurality of yieldable cantilever springs (27) are secured to one face of the spring plate. A spring plate as claimed in claim 10 wherein the springs are mounted on an upper face of the spring plate. A spring plate as claimed in claim 10 wherein the springs are mounted on both faces of the spring plate. A method of teeming molten metal from a vessel containing molten metal through a sliding gate valve secured to the vessel by means of a mounting plate, wherein the sliding gate valve is a sliding gate valve as claimed in any one of claims 1 to 9 or is a sliding gate valve which is used with a spring plate as claimed in any one of claims 10 to 12.

Inventors: KING PATRICK D, KING, PATRICK D.
Applicants: FLO CON SYST, FLO-CON SYSTEMS INC.
Application year: 1993
Main classification: B22D41
IPC codes: B22D41