GB2031567A - Sliding gate valve - Google Patents

Abstract

A sliding gate valve of the type in which refractory gates (17, 17') are sequentially disposed in operative position beneath the pour opening from a teeming vessel, such as a tundish, is effective to throttle the metal flow stream from the vessel. Means (84) for positioning the gates in order to control the degree of throttling of the flow stream are independent from the means (74) for disposing the gates in their working position within the valve mechanism whereby the flow stream can be terminated without adjusting the throttling configuration of the valve. Means are provided, when the valve employs a pour tube (19) attachment, for selectively changing gates and pour tubes in unison, or independently from one another. The valve mechanism and its replaceable refractory components are designed for the supply of fluids for cooling these members and for the injection of inert gas to stir molten metal in the flow passage during holding periods. <IMAGE>

Description

SPECIFICATION Sliding gate valve The present invention relates to sliding gate valves.

German Offenlegungschrift No. 2746265 describes a sliding gate valve arrangement for use on molten metal teeming vessels having the capability of throttling the flow of molten metal through the valve. The valve is of the type disclosed in United States Reissue Patent No. 27,237 in which refractory slide gates, either blank, imperforate gates or orificed gates, are sequentially positioned with respect to the vessel pour opening in order to initiate or terminate molten metal flow. The rate of flow through the valve can be regulated only by replacing the operative slide gate with one having an orifice of different diameter, thus precluding the ability to vary flow rates over an infinitely variable range. In the above mentioned throttling valve, flow regulation can be effected by adjusting the position of the slide gate orifice with respect to vessel pour opening.This characteristic of the throttling valve arrangement enables metal flow rates to be changed without the need to replace slide gates, thereby resulting in a significant reduction in the number of slide gates, and concomitant cost, required for valve operation.

Although the sliding gate valve arrangement of German Offenlegungschrift No. 2746265 represents a significant improvement over sliding gate valves of the prior art, it nonetheless has certain disadvantages. Principally, the configuration of the valve arrangement imposes certain stroke restrictions on slide gate throttling movement and thereby prevents the metal flow stream from being infinitely varied between its fully open position and its fully closed position without increasing the size and cost of the valve mechanism beyond the bounds of commercial feasibility. This deficiency in the valve makes it necessary to change slide gates for flow control in the extremely low flow ranges and for terminating flow.

Furthermore, in orderto prevent freezing of metal in the vessel pour opening, it is necessary to position a slide gate having a permeable plug beneath the pour opening for the injection of inert gas thus requiring the expenditure of additional slide gates for this purpose. Moreover, the valve enables the change of pour tubes only in conjunction with the replacement of an orificed slide gate with a blank gate for the purpose of terminating molten metal flow before effecting a pour tube change. Another disadvantage of the valve is its inability to positively ensure the alignment of a succeeding slide gate with that which is in an operative position in the valve for a rapid, effective slide gate change.

Accordingly, the present invention is directed in one of its aspects to an improved sliding gate valve organization of the type in which successive slide gates are sequentially positionable with respect to the pour opening of a teeming vessel and in which the slide gate can throttle the metal flow from the vessel over an infinitely variable range between the fully open condition of the valve and its fully closed condition.

The invention further improves upon prior art valves of the described type in that means are described which enable throttling to occur over the full range of metal flow without the need to change slide gates.

The sliding gate valve organization is also characterized by the ability to rapidly insert a blank gate when it is desired to terminate metal flow for safety or other reasons and with the ability to change pour tubes either in conjunction with or independently from a slide gate change.

Another feature of the present invention is the use of a sliding gate or particular configuration that enables its rapid insertion into its operative sealed position between the valve top plate and the pour tube support plate without danger of damaging either of these refractory members.

Another feature of the present invention is a top plate of particular configuration that enables the effective distribution of inert gas injection into the vessel pour opening when the valve is in its closed condition, such plate being configured to permit its fabrication by conventional refractory-forming processes without the need for expensive machining.

Yet another feature of the invention is the provision of means to effectively supply cooling air to the valve parts which are most sensitive to a high temperature atmosphere, including the seal springs and the refractory parts forming the pour opening of the vessel thereby reducing thermal deterioration of these parts.

The invention is further described, by way of example, with reference to the accompanying drawings, in which: Figure lisa vertical sectional view of the sliding gate valve of the present invention; Figure 2 is a vertical sectional view taken along line 2-2 of Figure 1; Figure 3 is a plan sectional view taken along line 3-3 of Figure 1; Figure 4 is a partially broken perspective representation of the mounting plate embodied in the present invention illustrating the flow paths for cooling air and inert gas therethrough; Figure 5 is a partially broken perspective representation of a top plate embodied in the present invention; Figure 6 is a plan view of a sliding gate constructed according to the present invention; Figure 7 is a perspective view of the sliding gate of Figure 6;; Figure 8 is a perspective view taken from above of the valve frame structure of the present invention prior to assembly; and Figure 9 is a perspective view taken from below of the valve frame structure of Figure 8.

In Figures 1 and 2 of the drawings there is shown a sliding gate valve organization 10 adapted for installation in operative relation to the pour opening 12 in the lining 14 of a teeming vessel 16, such as a tundish or the like, for teeming molten metal to the mold e.g. of a continuous caster (not shown).

Teeming is controlled by the manipulation of refractory slide gates or plates, that may be orificed as shown at 17 in Figures 2,6 and 7 or blank as shown at 17' in Figure 1,with respect to a refractory top plate 18. The organization 10 also includes replaceable pour tube assemblies 19 that form extensions of the valve for conducting the teemed molten metal stream to a caster mold. The valve organization 10 is adapted for mounting to the vessel 16 by means of threaded connectors 20 extending through holes 21 in the frame 22 attaching the same to the mounting plate 23 which is, in turn, attached to the vessel by means of bolts (not shown) that connect with a nut plate 24 underlying the vessel lining 14. A heat insulating pad 26 formed of asbestos, or the like, may be interposed between the mounting plate 23 and the vessel 16.

As best shown in Figure 4, the mounting plate 23 is a generally flat metal plate having a central opening 28 for reception of the lower end 30 of the refractory material forming the vessel pour opening 12. The upper surface of the mounting plate 23 contains, along its side edges, recesses 31 that communicate with bolt holes 32 for reception of the connectors 20 and their associated nuts 34.

The mounting plate 23 is provided with a plurality of internal fluid passages for conducting cooling air and inert gas during periods of valve operation. A first passage 36, concentric with the central opening 28, is defined by a recess formed in the wall of the opening and covered by a ring 38 that is weldedly attached to the plate in order to seal the passage. In addition, the plate is formed with a pair of oppositely extending elongated passages 40 and 42 extending about three sides of the plate and terminating in downwardly discharging ports 44 for supplying cooling air to the valve springs as hereinafter more fully described.An air inlet port 46 is provided at one side of the plate for delivering cooling air to the fluid passages 36 and 40, 42 which, as shown by the arrows 48, are connected in series whereby cooling air is first conducted about the annular passage 36 and then in opposite directions through the passages 40,42 before being discharged through the ports 44.

Also provided in the mounting plate 23 is an elongated passage 50 which, at one end, communicates with an inlet opening 52 at the side of the plate for connection with a source of inert gas and at the other end, with a downwardly directed discharge opening 54 adapted to communicate with gas supply means in the valve top plate 18 as hereinafter described.

The valve frame 22, formed essentially of a machined metal casting stiffened by members 56 is best illustrated with particular reference to Figures 8 and 9. This frame 22 contains the operating parts of the valve organization and is adapted for attachment to the mounting plate 23, or release therefrom, as an assembled unit through the connectors 20. The frame 22 comprises three principal sections, indicated generally in Figure 3 as plate loading section 58, operating section 60 and plate discharge section 62. Adjacent the plate loading section 58 the frame 22 attaches, through connectors (not shown) engageable with threaded holes 64 (Figure 8), bracket means 66 for mounting feeding motor 68. The feed motor 68 comprises a fluid operated cylinder 70 having a reciprocable piston attaching a piston rod 72 and pusher 74.A second set of motors, termed "throttling motors" are attached to the frame 22 adjacent the operating section 60 thereof. These motors 76 are oppositely acting and are operated independently of the feed motor 68. They each comprise an operating cylinder 78 mounted to the frame by bracket 80 which attaches to the frame side wall by connectors engageable with the holes 82.

The cylinders 78 each contain a reciprocable piston whose rod 83 attaches a laterally elongate connecting brace 86 which connects slide pins 88 that are guidingly received in openings 90 in the frame side wall and attach throttling rails 84 and 84' that operate to manipulate a slide plate disposed in the operating section 60 of the frame. Rail 84' is of a length shorter than rail 84 in order to accommodate passage of a plate through the loading section 58 of the frame.

The interior of the frame 22 is configured to define communicating paths of travel for slide plates 17 or 17' and pour tube assemblies 19 between the respective frame sections 58, 60 and 62. The loading section 58 of the frame 22 heredescribed is defined by laterally extending guideways 92 and 94 adapted to pass slide plates 17, 17' and pour tube assemblies 19 respectively. The guideway 92 is vertically spaced from guideway 94 by oppositely extending slide rails 96 that serve to support the slide plates that are loaded in the valve. The bottom of guideway 94 is defined by a similar set of slide rails 98 that support pour tubes 19 for loading. Rub rails 99 along the roof of the frame in this section serve to vertically position a slide plate 17 as it is moved from the loading section 58 of the valve to the operting section 60 thereof.

It will be appreciated that frame 22, as depicted in Figures 8 and 9, is adapted for slide plate or pour tube insertion from either the right or left hand side by the provision of identical guideways 92' and 94' on the opposite side of the frame. When the guideways 92 and 94 are selected for use, those guideways indicated as 92' and 94' on the opposite side of the frame are closed by a stuffer member 100 comprising a backing plate 102 threadedly connectable to the frame 22 at holes 104 (Figures 8) and vertically spaced stop plates 106 and 108 that fill the guideways 92' and 94' effectively preventing movement of a pour tube beyond its desired position adjacent the pusher 74. Obviously, loading from the opposite side of the frame can be readily effected by simply moving the stuffer member 100 from passageways 92' and 94' to the opposite side of the frame where it will fill the passageways 92 and 94.

The operating section 60 of the frame 22 contains a rectangular openign 110 in the upper surface thereof for reception of a stationary refractory top plate 18 whose central orifice 112 aligns with the pour opening 12 from the vessel and defines the inlet to the valve 10. Vertically spaced below the opening 110 the frame 22 is provided with oppositely spaced bases 114 that cooperate with the upper wall of the frame to define a cavity 115. The bases 114 are provided with laterally spaced threaded holes 116 which receive connectors 118 for mount ing a series of spring biased levers 120 that operate to retain the pour tube assembly 19, slide plate 17 or 17' and top plate 18 in surface-to-surface sealed relation. The levers 120 pivot upon rockers 122 retained by the connectors 118 and are spring biased by headed push pins 124 movably mounted in holes 126 in the frame.The holes 126 are counter bored at their upper ends at 127 to provide seats for the push pin heads 128 and for springs 130 that bear between the push pin heads and the facing surface of mounting plate 23.

As shown in Figure 2 the holes 126 in the frame 22 are caused to communicate with the ports 44 in the mounting plate 23 whereby cooling air is supplied to prevent overheating of the springs 130. Desirably, the ports 44 contain discharge orifices 132 in order to effectively distribute cooling air to the respective spring assemblies.

Opposite walls of the valve frame 22, adjacent the operating section 60, are provided with vertically spaced pairs of aligned holes, indicated as 196 and 198 respectively. Each pair of aligned holes is adapted to receive a selectively positionable stop pin 200 that traverses the respective paths of travel of the slide plate or pour tube assembly and is operative during plate changing procedures to obstruct movement of either the slide plate 17 or pour tube assembly 19 when it is desired to replace the other. Similar holes 196' are provided in rails 84 and 84' to accommodate passage of the stop pin 200 through these members. When the simultaneous replacement of both the slide plate 17 and the pour tube assembly is desired the stop pin 200 is withdrawn from the frame completely leaving both paths of travel free of obstruction.Under normal operation conditions the stop pin 200 is retained in the lower pair of holes 198 to leave the slide plate travel path free of obstruction in order to permit rapid termination of molten metal flow as hereinafter described.

The discharge section 62 of the frame 22 is formed by vertically spaced guideways 134 and 136 opening at the end of the frame. The guideways 134 and 136 are defined by stepped shoulders 138 and 140 formed in the longitudinal extensions of the bases 114 and are adapted to slidably guide the slide plates 17 or 17' and pour tube assemblies respectively from their positions in the operating section 60 of the valve to a point of discharge as hereinafter described.

As shown best in Figure 3, the throttling rails 84 and 84' are disposed in the frame 22 at substantially the same elevation as slide plate loading guideway 92. Rail 84 is longerthan rail 84' extending substan tially the full length oftheframe interior. Rail 84', on the other hand, is shorter than rail 84 by an amount to permit passage of a slide plate 17 from the guideway 92 into position with respect to pusher 74 upon loading of these members.Rail 84 is further provided along that portion of its length that faces the guideway 92 with a plurality of longitudinally spaced magnets 142 here shown as being six four-pole permanent magnets, the function of which is to prevent dislodgement of a slide plate 17 or 17' in the loaded "read" position, hereinafter described, from the rail 84 as it is moved during the performance of the throttling function of the valve.

The slide plates 17, 17', top plate 18 and pour tube assemblies 19 ofthevalve organization 10 each essentialy comprise a refractory material encased in a metal frame. The pour tube assembly 19 contemplated for use in the described organization is of essentially conventional construction consisting of an elongated cylindrical tube 144 having an axial opening 145. The tube 144 can be of a length to permit its lower end to extend into a caster mold, or the like. (not shown). The upper end of the tube 144 is adapted for reception into a recess 146 in the lower surface of a generally flat, rectangular refractory plate, termed the tube holder plate 148.The plate 148 contains a through-opening 149 coaxial with tube opening 145 and is enclosed about the exposed portion of its bottom and about its peripheral sides by a metal casing 150. As shown in the drawing, a mortar cement is employed to seal the joint between the upper end of the tube 144 and the holder plate 148 and to attach the holder plate within the metal enclosure. The metal enclosure may be provided with a depending skirt 152 which serves to protect the mortared joint and to stiffen the enclosure bottom surface. A heat resistant material such as asbestos rope (not shown) can be used to fill the space 153 between the skirt and the tube.A secondary attachment between the tube 144 and the holder plate can be effected by provision of a collar 154 defining a shoulder 156 adjacent the upper end ofthe tube for engagement buy a retention ring 158 which is releasably secured to the metal casing 150 by threaded fasteners, or the like (not shown). The openings 145 in the pourtube 144 and 149 in plate 148 are preferably formed of a diameter slightly greater than that of the slide plate orifice in order to permit metal drainage from the passage upon throttling the valve to a fully closed condition.

The top plate assembly 18 of tube presentorganiza- tion is shown in Figures 1,2 and 5. The assembly 19 comprises a rectangular refractory plate 160 set by mortar in a metallic -casing 162 of generally Lshaped cross section that extends about the peripheral sides of the plate. The upper surface 164 of the plate 160 extends above the upper edge of the casing and is provided with a polished finish to provide a smooth surface-to-surface contact with the lower surface of mounting plate 23 and the vessel refractory lining 14 when the assembly is in its operative position in the valve organization. Plate 160 is provided with a centrally disposed stepped through opening 166 in order to receive a permeable refractory insert 168 having an axial opening defining the molten metal flow passage 112 through the plate. The insert 168 has an exterior surface 172 that is stepped in a fashion complimentary to that of the plate opening 166 with the outermost steps being adapted for cemented engagement with the mating steps of the opening but with the intermediate step of a significantly smaller diameter than that of the intermediate step of the opening. In this way there is defined an annular passage 174 about the circumference of the insert 168 for the supply of inert gas through the insert into the metal flow passage 112.

The refractory plate is provided with an oblique channel 176 that opens at the top of the plate at 178 and being positioned to communicate with the opening 54 in the lower surface of the mounting plate 23 when the valve is assembied. There is thus provided a convenient means for supplying inert gas into the metal flow passage 112 during periods when the valve is closed thereby to stir the meta in flow passage and thus prevent its freezing. By forming the annulus in this fashion, so-formed refractory top plates can be fabricated by conventional refractory forming methods without the need for expensive machining with collapsible or multi-part machine tooling.

The slide plate assemblies utilized in the valve organization may be blank or imperforate as the type shown at 17' in Figure 1 or may contain a through opening 180 as the type shown at 17 in Figures 2,6 and 7. Blank plates 17' are employed, as shown in Figure 1, to prevent metal flow through the valve while orificed plates 17 are employed when it is desired to controllably pass molten metal through the valve as hereinafter described. Both slide plate assemblies 17 and 17' are fabricated in an identical manner comprising a generally rectangular refractory plate 182 which is slightly shorter in the feed direction indicated as F in Figures 6 and 7 than in the throttling direction indicated as T. The plate 182 is cemented within a metal casing 184 that encloses the peripheral sides of the plate.The casing 184 is provided with a shoulder 186 intermediate its upper and lower edges for seating engagement on the throttling rails 84 and 84' and for sliding engagement upon the slide rails 96 in the loading section 58 ofthe valve and the shoulders 138 in the discharge section 62 thereof. The refractory plate 182 is formed at 188 with a mating shoulder conforming to that in the casing.

The lower portion of the casing, indicated as 190, is formed with an enlarged radius curvature providing a guiding cam surface to enable the respective slide plate assemblies when being moved by pusher 64 into the operating section 60 of the valve to be guidingly urged up and over the upper edge of the pourtube holder assembly without causing damage to either member.

The lower portion of the plate 182 adjacent the enlarged radius portion 190 of the casing is tapered as shown thus to provide an enlarged receptacle 192 for mortar between the plate and the metal casing.

The enlarged mortar bed in this region of the assembly operates to cushion the plate during movement of the plate across the tube holder assembly 19 and when the plate is manipulated by the movable rails 84, 84' during periods of throttling.

Slide plate assembly 17 differs from assembly 17' in that the latter is imperforate while the former contains the molten metal flow opening 180. The position of the opening 180 in the refractory plate is critically located along the longitudinal centerline of the plate but offset from the center point of the plate toward the left in Figure 2 by an amount equal to one-half the length of stroke of the throttling pins 88 thereby permitting the opening 180 to be vertically aligned with the top plate opening 112 for full flow of metal through the pour passage with the plate fully stroke to the right as viewed in Figure 2 with the rail 84' in abutment with the wall 194 of the cavity 115.

With the plate 17 being fully stroked to the left and the rail 84 abutting wall 196 the opening 180 is moved completely out of registry with the opening 112 thereby effecting termination of molten metal flow through the valve. By operation of the throttling motors 76 the position of the opening 180 in the plate 17 can be adjusted to any desired iocation with respect to the top plate opening 112 intermediate these full stroke positions thereby to alter the effective size of the molten metal flow passage through the valve for regulating molten metal flow therethrough.

Atypical commercial embodiment of the slide plate assembly 17 is approximately 10.9 inches along in the feed direction F and 12.9 inches long in the throttling direction T with the center of the opening 180 having a three inch diameter being offset from the plate centre point approximately 1.75 inches thereby providing about one-half inch of refractory material between the holes 112 and 180 with the plate 17 in the shutoff position. The operation of the hereindescribed valve organization 10 is as follows: The valve frame 22 is attached to the mounting plate 23 at the bottom of the teeming vessel 16 as shown in Figure 1 with the top plate 18, a blank slide plate 17' and a pour tube assembly 19 preassembled in the operating section 60 of the valve frame. The flow passage 112 through the top plate 18 is thus vertically aligned with the pour passage 12 through the vessel lining 14.When molten metal is deposited in the vessel its flow through the valve is prevented due to the obstruction in the flow passage presented by the flow-impervious blank slide plate 17'. During such metal holding periods an inert gas, such as argon or nitrogen, is admitted to the pour passage 112 of the top plate through passages 52 in the mounting plate 23 and 176 in the top plate into the annulus 174 about insert 168 from whence it permeates the porous wall of the insert to enter the passage 112. Entry of inert gas in this fashion serves to stir the molten metal in the obstructed flow passage and thereby prevents its freezing therein.

Also, cooling air is admitted to the valve through inlet 46 in the mounting plate 23 from whence it flows seriatim through annular passage 36 about the lower region of the vessel lining 14to cool the refractory material in this region and thence through passages 40, 42 to discharge from ports 44 to cool the springs 130.

With the throttling mechanism disposed to place the rails 84 and 84' in the position shown in Figure 2 with rail 84 in abutment with cavity wall 196, an orificed slide plate 17 is inserted manually into the valve loading section 58. The slide plate 17 is inserted through the guideway 92 with the plate shoulders 186 in sliding engagement upon the slide rails 96. The slide plate 17 is moved until its leading edge surface abuts the rail 84, being retained thereagainst by the magnets 142, thus placing the slide plate 17 in its "ready" position adjacent the pusher 74 of the feed motor 68.Thereafter, the feed motor 68 is actuated to cause the pusher 74 to move the slide plate 17 from its "ready"position into the operating section 60 of the valve frame 22 between the top plate 18 and pour tube assembly 19 by displacing the blank plate 17 which slides along the shoulders 138 to the discharge section 162 from whence it exits the frame. An effective surface-tosurface seal between the respective plates is provided by the spring-biased levers 120 which urge the tube holder plate 148 upwardly against the slide plate 17 and that, in turn, upwardly against the top plate 18. Due to the presence of the enlarged radius 190 on the casing 184 of the slide plate 17 the moving plate is guided across the facing edge of the spring biased pour tube holder plate 148 without damage that plate.The feed motor 68 is then actuated in the reverse direction to retract the pusher 74to the position shown in Figure 1 whereupon, for safety reasons, a blank slide plate 179, as shown in Figure 3, is inserted into its "ready" position in the valve frame 22 in the same manner as described above in connection with the insertion of the slide plate 17.

When it is desired to initiate molten metal flow through the valve the flow of inert gas to the passage 112 is terminated and the throttling motors 76, which operate in unison, are actuated to move the rails 84, 84' and the retained slide plate 17 laterally of the cavity 115. Normally, the motors 76 will be actuated to move the rails 84, 84' to place rail 84' into abutment with wall 194 of cavity 115 thereby placing the orifice 180 of slide plate 17 in axial alignment with the opening 112 in the top plate 18. This defines the "full-open" position of the valve. Alternatively, however, it will be appreciated that, where molten metal flow is desired at a rate less than full flow, the throttling motors can be controlled to locate the slide plate 17 at any intermediate position betwee "full open" and "full close" to produce the desired intermediate flow rate.Furthermore, during the course of teeming the position of the slide plate can be altered, either to increase or decrease the rate of molten metal flow through the valve as desired by controlling the operation of the throttling motors 76 which impart throttling movement to the slide plate 17 and its orifice 180 with resect to the top plate pour opening 112.

The invention permits ready replacement of both the slide plate 17 and the pour tube assembly 19, either singly or jointly. When it is desired to replace a spent slide plate 17 the stop pin 200 is inserted through holes 198 in the valve frame 23 to prevent movement of the pour tube assembly. The blank plate 17' is withdrawn from the "ready" position adjacent the pusher 74 and a replacement slide plate 17 inserted in its stead. The feed motor 70 is then actuated to move the replacement plate into the operating section 60 of the valve while discharging the spent plate through the discharge opening 62.

This procedure can be accomplished with the throttling rails 84, 84' disposed in any lateral position across the operating section 60 since the replacement plate 17 is retained on the rail 84 by means of the magnets 142. Thus, when installed in the operating secton 60, the replacement plate 17 will assume the same throttling position of the spent plate it replaced.

When it is desired to replace a pour tube assembly 19, the throttling rails 84, 84' are operated by the throttling motors 76 to move the slide plate 17 to the fully closed position shown in Figure 2 and the safety blank 17' withdrawn from thevalve frame. The stop pin 200 is next removed from holes 198 and inserted in holes 196, 196' to prevent movement of the operative slide plate 17. The replacement pour tube assembly 19 is then manually inserted through guideway 94 of the loading secton 58 of the valve frame 23 to a position adjacent the pusher 74 whereupon the feed motor 70 is actuated to move the replacement pour tube assembly 19 into its operative position beneath the slide plate 17 in the section 60 while expelling the spent pourtube assembly through the guideway 136 of the discharge section 62.

When, alternatively, it is desired to change both a slide plate 17 and a pour tube assembly 19, the throttling motors 76 are actuated to move rails 84, 84' and the operative slide plate 17 to the fully closed position and the stop pin 200 is withdrawn from the valve frame. The replacement slide plate 17 and pour tube assembly 19 are inserted through guideways 92 and 94 respectively in the loading section 58 to their "ready" positions adjacent the pusher 74. Upon actuation of the feed motor 68, the replacement slide plate and pour tube assembly are simultaneously moved into position into the operating section 60 while expelling their spent counter-parts through guideways 134 and 136 of the discharge section 62.

An important characteristic of the hereindescribed valve organization is the ability to rapidly terminate molten metal flow through the valve and independently of its throttling function. This characteristic is achieved by virtue of the fact that the operation of the feed motor 68 which effects plate replacement in the valve is totally indepen dent from that of the throttling motors 76 and that slide plate 17 can be changed regardless of the throttling position of the operative slide plate located in valve section 60.

Thus, during the course of normal valve operation a blank slide plate 17' is preferably retained in the "ready" position adjacent pusher 74. This plate, like all plates in the "ready" position, is secured to the rail 84 by the magnets 142 and thus is caused to move laterally back and forth with the operative slide plate 17 thereby insuring that the former is always longitudinally aligned with the latter. If for any reason it becomes necessary to rapidly terminate the flow of molten metal, as for example, due to malfunction of the casting process, the feed motor 68 need only be actuated to replace the operative orificed slide gate 17 with the blank gate 17'. The advantage of this feature can be appreciated when it is considered that a plate change can be effected by the feed motor in less than .2 second as contrasted with a period of approximately 2 seconds duration that is required to move the operative slide plate from its fully open position to its fully closed position by the throttling motors 76.

Claims (23)

1. A gate for controlling in a valve the flow of liquid metal from the pour opening of a teeming vessel, comprising a generally rectangular refractory body having a longitudinal axis and a lateral axis transverse thereto and an opening through said body which defines a metal flow orifice and which is disposed on the lateral axis of said gate in offset relation to said longitudinal axis.

2. A gate as claimed in claim 1 in which the extent of said offset is in excess of the radius of said orifice.

3. A gate as claimed in claim 1 or claim 2, including a metal casing encircling the sides of said refractory body, and shoulders in said causing about all sides of said body and defining surfaces for guided movement of said gate in a direction parallel to both the longitudinal and lateral axes thereof.

4. A gate as claimed in claim 3 in which said casing includes a portion forming a convexly arcuate cam surface subjacent said shoulders at least along the lateral sides of said body.

5. A gate as claimed in claim 4, in which the arcuate cam surface of said casing is spaced from said refractory body, and a cushion of mortar fills the space therebetween.

6. A valve for controlling the flow of liquid metal from the pour opening of a teeming vessel, compris ing a frame for connection to said vessel and having a hollow interior, a top plate fixedly mounted in said frame and having a through-opening for fluid com munication with the vessel pour opening, opposed gate supporting rails mounted in said frame for slidably supporting refractory gates for sequential movement through said frame along a path of travel having gate loading, operating and discharge sec tions, at least one refractory gate slidably mounted on said rails, said gate comprising a generally rectangular refractory body having a longitudinal axis aligned with said rails and a lateral axis transverse thereto, and an opening through said body which defines a metal flow orifice for registry with said top plate opening and which is disposed on the lateral axis of said gate in offset relation to said longitudnal axis, first moving means attached to said frame and operative to move refractory gates se quentially along said rails, and second moving means operably independent of said first moving means and operatively connected to said rails to move said gate along a second path of travel transversely of said frame to vary the degree of registry of the gate orifice with said top plate opening between a position of coaxial alignment therewith and a position out of registry therewith.

7. A valve as claimed in claim 6, in which the frame has a lateral opening communicating with the gate loading section for lateral insertion of the gates, the rail adjacent to said lateral opening being interrupted by said opening and the rail opposite to said lateral opening being substantially coextensive with all three of said frame sections and including means for retaining a gate thereon in the loading section of said frame.

8. Avalve as claimed in claim 7, in which the retaining means comprises at least one magnet.

9. A valve as claimed in any one of claims 6 to 8, including pour tube supporting rails disposed in said frame subjacent to and substantially coextensive with said gate supporting rails, and a pour tube assembly having a tube support plate engageable with the rails for sliding movement therealong.

10. Avalve as claimed in claim 9 in which said first moving means includes means operative to move said pour tube assembly along its rails.

11. Avalve as claimed in claim 10, including means for selectively obstructing movement of the gates and the pour tube assembly to enable said first gate moving means to move said gates and pour tube assemblies singly or jointly.

12. A valve as claimed in claim 11 in which said obstructing means comprises a stop pin selectively positionable either in a position traversing the path of travel of the gates or in a position traversing the path of travel of the pour tube assembly.

13. A valve as claimed in any one of claims 9 to 12, in which the pour tube rails each include a series of levers pivotally attached to said frame and having one end engageable with said pour tube support plate, and springs in said frame providing an upward bias to said one end of each of said levers.

14. A valve as claimed in claim 13, including a valve mounting plate for interposition between said frame and said vessel for effecting a connecting therebetween, the mounting plate having means for supplying cooling fluid to ports in said frame in overlying relation to said springs.

15. A valve as claimed in any one of claims 6 to 14 in which said top plate includes an annular passage concentrically disposed with respect to said through-opening and means for supplying an inert gas to said passage.

16. A valve as claimed in claim 15, in which the through opening in said top plate has axially spaced steps of progressively greater diameter from one end of said opening to the other, and receives an apertured porous plug which has an exterior surface formed of axially spaced steps of progressively reduced diameter from one end of said plug to the other, the endmost steps on said plug being cemented to the corresponding steps in the axial opening in said body, and the step on said plug intermediate said endmost steps having a diameter less than that of the corresponding step in the axial opening so as to define said annular passage.

17. A valve as claimed in claim 16 including a metal casing cemented about the periphery of said top plate.

18. A refractory plate for use in a valve for controlling the flow of liquid metal from a teeming vessel, comprising a refractory body having a through opening which has axially spaced steps of progressively greater diameter from one end of said opening to the other, and receives a porous plug which has an exterior surface formed of axially spaced steps of progressively reduced diameter from one end of said plug to the other, the endmost steps on said plug being cemented to the corres ponging steps in the axial opening in said body, and the step on said plug intermediate said endmost steps having a diameter less than that of the corresponding step in the axial opening so as to define an annular passage.

19. A valve for controlling the flow of liquid metal from the pour opening of a teeming vessel, comprising a frame for connection to said vessel and having a hollow interior, opposed gate supporting rails mounted in said frame for slidably supporting refractory gates for sequential movement through said frame along a path of travel having gate loading, operating and discharge sections, first moving means attached to said frame and operative to move refractory gates sequentially along said rails, and second moving means operably independent of said first moving means and operatively connected to said rails to move said gate along a second path of travel transversely of said frame to vary the degree of registry of the gate orifice with said top plate opening between a position of coaxial alignment therewith and a position out of registry therewith, the frame having a lateral opening communicating with the gate loading section for lateral insertion of the gates, the rail adjacent to said lateral opening being interrupted by said opening and the rail opposite to said lateral opening being substantially coextensive with all three of said frame sections and including means for retaining a gate thereon in the loading section of said frame.

20. A valve for controlling the flow of liquid metal from the pour opening of a teeming vessel, comprising a frame for connection to said vessel and having a hollow interior, opposed gate supporting rails mounted in said frame for slidably supporting refractory gates for sequential movement through said frame along a path of travel having gate loading, operating and discharge sections, first moving means attached to said frame and operative to move refractory gates sequentially along said rails, and second moving means operably independent of said first moving means and operatively connected to said rails to move said gate along a second path of travel transversely of said frame to vary the degree of registry of the gate orifice with said top plate opening between a position of coaxial alignment therewith and a position out of registry therewith, the valve having pour tube supporting rails disposed in said frame subjacent to and substantially coextensive with said gate supporting rails, and a pourtube assembly having a tube support plate engageable with the rails for sliding movement therealong upon operation of said first moving means, the valve also having means for selectively obstructing movement of the gates and the pour tube assembly to enable said first gate moving means to move said gates and pour tube assemblies singly or jointly.

21. A gate for controlling in a valve the flow of liquid metal from the pour opening of a teeming vessel, constructed substantially as herein before described with reference to and as illustrated in Figures 2, 6 and 7 of the accompanying drawings.

22. A valve for controlling the flow of liquid metal from the pour opening of a teeming vessel, constructed and adapted to operate substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

23. A refractory plate for use in a valve for controlling the flow of liquid metal from a teeming vessel, constructed substantially as hereinbefore described with reference to and as illustrated in Figure 5 of the accompanying drawings.