Patent Publication Number: US-5836485-A

Title: Sliding gate valve assembly for a vessel containing molten metal

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to sliding valves for vessels containing molten metal. A housing frame has a refractory base plate and a refractory sliding plate mountable therein. The refractory sliding plate can be pressed against the refractory base plate by spring elements. The refractory sliding plate is arranged in a slider unit, and the slider unit is movable back and forth in the housing frame by a drive member. 
     2. State of the Prior Art 
     One known sliding gate valve is disclosed in patent publication DE-C 2523928. The sliding gate valve disclosed in this publication is suitable in particular for a converter forming a vessel containing molten metal. A sliding gate valve assembly is pre-assembled with known refractory wear parts, including a sliding plate, a base plate, and a discharge sleeve. The pre-assembled unit is secured by eye bolts and guide pegs to a frame attached to a tap of the converter. With this way of attaching the pre-assembled unit, it must be ensured that the projecting base plate in the valve engages in a groove of a front-most tap brick of a tapping passage in the converter, and that a sealed connection is sealed by mortar inserted between the front-most tap brick and the projecting base plate. The mortar subsequently hardens between them so that molten steel cannot leak out between the base plate and the tap brick. Leakage of liquid molten metal between the refractory components can result in the destruction of the entire sliding gate valve assembly. 
     The valve plates are required to be regularly replaced in this known sliding gate valve, because they are subjected to relatively intense wear. A certain amount of effort, however, is required for this type of replacement operation because the valve has to be removed from the hot converter and then opened. The plates have to be replaced, and the valve subsequently has to be reinstalled on the tap hole of the converter. Upon reinstallation, it again has to be ensured that the connection between the base plate and the refractory tap brick adjacent to the base plate are completely sealed with mortar. 
     SUMMARY OF THE INVENTION 
     It is the object of the present invention to provide a sliding gate valve of the type discussed above that is substantially removable from molten metal vessel and that can be installed on the molten metal vessel in a relatively simple manner and in an automated operation. It is a further object of the invention to ensure that the seal between a refractory base plate and a sliding plate, as well as between the refractory base plate and the head member adjacent to the refractory base plate, is complete. 
     In accordance with the present invention, a sliding gate valve arrangement is provided in which molten metal vessel has an outlet and guide tracks secured to the vessel extending transverse to the outlet. A housing frame is slidably mountable on the guide tracks. The housing frame has a refractory base plate and a slider unit therein as well as a plurality of spring packets or spring elements. The slider unit comprises a refractory sliding plate, and the refractory sliding plate is sealingly pressable into engagement with the refractory base plate by the spring elements. The drive element is connectable with the slider unit for moving the slider unit back and forth. The guide tracks have a predetermined length such that the housing frame, when disposed on the guide tracks, is slidable over a predetermined distance between a first position in which the housing frame positions the refractory base plate and the slider unit below the outlet of the molten vessel and a second position in which the housing frame is released from the guide tracks and the molten metal vessel. 
     A coupling is provided on the housing frame. A manipulator is connectable to the coupling of the housing frame for moving the housing frame on the guide tracks between the first position and the second position for the purpose of removing and installing the housing frame on the vessel. 
     The coupling preferably comprises a coupling peg, while the manipulator preferably comprises an actuating cylinder and a coupling sleeve attached to the actuating cylinder. The coupling peg and the coupling sleeve are connectable together to form a bayonet connection. The coupling peg and the coupling sleeve, furthermore, when coupled together, form a rigid connection. 
     The housing frame, furthermore, has sides having respective support arms thereon. The guide tracks are preferably L-shaped and preferably arranged parallel to one another. Each of the L-shaped tracks defines a guideway having an end portion lower than the guideway. Accordingly, the support arms can be guided onto the guideways. 
     The guide tracks define a means for sealing by pressing refractory sliding plate into engagement with the refractory base plate and the refractory base plate into engagement with the outlet through the spring elements when the manipulator is coupled to the coupling of the housing frame. The housing frame is moved by the manipulator into position by the guide tracks, and the manipulator moves the housing frame from the second position to the first position over the predetermined distance. 
     The outlet of the molten metal vessel has a flat lower surface for engagement with the refractory base plate. The guide tracks slope towards the flat lower surface from an open end thereof. Furthermore, the guide tracks preferably slope at a first rate and have an end portion at the open end thereof that slopes at a second rate greater than the first rate. 
     The vessel further comprises a first coupling part that is mounted thereon, and the housing frame preferably comprises a second coupling part mounted on the housing frame for connection with the first coupling part. One of the first and second coupling parts is a coupling sleeve, and the other is a member that is insertable into the sleeve. The coupling sleeve preferably has an internal dog, with the member having a notch for receiving the dog. One of the coupling sleeve and the member is rotatable between a position in which the coupling sleeve and the member are relatively movable and another position in which the internal dog engages the notch and the coupling sleeve and member are linearly fixed. 
     The coupling sleeve is preferably supported on the vessel by a bracket. The coupling sleeve further has an opening therein receiving a push rod therethrough. The member has a connecting portion therein connectable with the push rod. The push rod is connected with the drive element, and the connecting portion is connected with the slider unit. 
     The manipulator preferably has a gripper for engaging molten metal vessel for the purpose of positioning the manipulator relative to the vessel. The vessel includes an adaptor plate that surrounds the outlet, the adaptor plate having centering pegs thereon for engagement by the gripper. 
     The guide tracks and the spring packets are arranged such that the housing frame is not pressed by the spring packets due to contact with the guide tracks until shortly before the housing frame reaches the first position when moved from the second position to the first position by the manipulator. The support arms have a longitudinal extent along the sides of the housing frame, and the spring packets are distributed along the longitudinal extent of the support arms. The guide tracks have substantially the same longitudinal extent as the support arms. 
     The spring packets preferably comprise guide pegs having springs disposed thereon. The pegs have lower engagement surfaces for engagement with the guide tracks. The guide tracks have engagement surfaces for engagement with the lower engagement surfaces of the pegs. The lower engagement surfaces of the pegs define lines that are parallel to the guide tracks. The guide tracks extend at an acute angle relative to the direction of movement of the housing frame. 
     With the sliding gate valve assembly according to the present invention, the refractory plates, including the refractory base plate, the sliding refractory plate, and the refractory head member in the adapter plate, may be replaced without relatively time consuming manual work having to be performed on the hot molten metal vessel, especially if the vessel is a converter. When sliding gate valves are used on a converter, the fact that the refractory plates have a length up to 600 millimeters, or longer, must be taken into account. As such, they can hardly be replaced manually. This problem is also solved by the above features of the present invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     An example of a preferred embodiment of the present invention will be described below with reference to the accompanying drawings in which: 
     FIG. 1 is a longitudinal sectional view of a sliding gate valve assembly according to the present invention; 
     FIG. 2 is a bottom view of the sliding gate valve assembly of FIG. 1; 
     FIG. 3 is a partial cross-sectional view of a sliding unit mounted on guide tracks of an adapter plate of the sliding gate valve assembly according to the present invention; 
     FIG. 4 is a longitudinal sectional view showning details of support arms of the housing frame mounted on the guide tracks of FIG. 3; 
     FIG. 5 is an end view of a coupling arrangement according to the present invention; and 
     FIG. 6 is a schematic view of a manipulator, a molten metal vessel and the sliding gate valve assembly according to the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring initially to FIG. 1, a sliding gate valve 20 is provided at an outlet 12 of a vessel 10 containing molten metal. The vessel 10, in FIG. 1, is not specifically illustrated. However, the vessel is a converter in which the outlet 12 is arranged along an upper region of a sidewall of the vessel. When the vessel 10 is emptied, it is tilted to allow the molten metal to flow to the outlet 12. Subsequently, the molten metal flows through the outlet 12, also referred to as a tap, into a ladle or the like. 
     Of the vessel 10, only an outlet socket 14 is shown. The external surface of the socket 14 is metallic. Arranged inside the socket 14, shown in part, are a refractory inlet sleeve 11, a refractory sleeve 16 surrounding the sleeve 11, and a mortar bed 15. Otherwise, the vessel 10 is similar to the vessel illustrated in publication DE-C 2523928, discussed above. 
     An adapter plate 40 is removably mounted to an end surface of the outlet socket 14. The sliding gate valve assembly 20, in turn, is secured to the adaptor plate 40. 
     The sliding gate valve 20 includes a housing frame 22. The housing frame 22 houses a stationary refractory base plate 25 and a slider unit 23 holding a sliding plate 26. The sliding plate 26 is sealingly pressed against a lower sliding surface 28 of the refractory base plate 25. The slider unit 23 is moved back and forth by a drive element that is connected to a push rod 29. The push rod 29 is connectable to the slider unit 23. Accordingly, the sliding gate valve 20 can be moved into an open position as illustrated in FIG. 1, and into a closed position. The sliding plate 26 moves relative to the refractory base plate 25, accordingly. 
     Adjacent to the sliding plate 26 is a refractory discharge sleeve 32 through which molten metal flows out of the vessel 10 into a ladle or the like. It is noted that in use the sliding gate valve 10, with this arrangement, assumes only either an open position or a closed position with the converter vessel 10. There is therefore no controlled discharge of the volume of metal that flows out of the vessel 10. 
     The refractory base plate 25 has a plane upper slide surface 27 parallel to the lower sliding surface 28. The refractory base plate 25 is stationary in the direction of the lower sliding surface 28, but is disposed and arranged so as to be moveable in a direction perpendicular to the lower sliding surface 28 within the housing frame 22. Accordingly, the refractory base plate 25 is capable of being pressed against a refractory head member 42. The refractory head member 42 is securable to the outlet 12. As such, the refractory base plate 25 and the refractory head member 42 together define a sealed point of disconnection. 
     The refractory base plate 25 is enclosed within a cassette 25&#39; that is mounted to be moveable in the housing frame 22 in a direction transverse to the longitudinal dimension of the plates, as discussed above. This arrangement makes the removal and installation of the housing frame from and to the vessel 10, together with the slider unit 23 and plates 26 and 28, possible. 
     Guide tracks 52 are attached to the adapter plate 40 on the vessel 10 and extend in a direction transverse to the outlet 12 of the vessel. The housing frame 22 is mounted together with the sliding plate 26 and the refractory base plate 25 beneath the outlet 12 so as to be longitudinally moveable on the guide tracks 52. The housing frame 22 is capable of being moved a predetermined distance from its mounted position so as to move to a release position. 
     On one end of the housing frame 22 is a coupling peg 62. The coupling peg 62 forms a means for connecting the housing frame 22 to a manipulator 80 (to be described later). The manipulator 80 can thus be used, by engagement with the peg 62, to move the housing frame 22 into a outer position on the guide tracks 52. Preferably the coupling peg 62, in its connection with the manipulator 80, forms a rigid bayonet connection. 
     The refractory head member 42 referenced above is an annular member that has a flat end surface 43 on its underside and a circular groove 44 on an upper surface thereof. An annular projection on the discharge sleeve 11 fits into the circular groove 44. Between the end of the discharge sleeve 11 and the circular groove 44 is preferably provided a setting mortar. A flange 42&#39; surrounds the head member 42. The flange 42&#39; is fixed from below in an annular recess 41 of the adapter plate 40 by a suitable fastening arrangement 45, such as bolts. When the sliding gate valve assembly 20 is removed along with the housing frame 22, the head member 42 can also be released and replaced. In the assembled state, the lower flat end surface 43 of the head member 42 projects beyond, i.e. below, the lower surface of the adapter plate 40. This thus permits the flat end surface 43 to contact the upper surface 27 of the refractory base plate 25. It is noted that the upper surface 27 of the refractory base plate 25 projects beyond, i.e. above, the housing frame 22. 
     High grade refractory inserts, for example comprising zirconia, may be embedded in a refractory base material of each of the refractory base plate 25, the sliding plate 26, and a discharge sleeve 32. Furthermore, a metallic band may surround the refractory base material. 
     A coupling device 30 is illustrated at the right hand side of each of FIGS. 1 and 2. The coupling device 30 is secured to the adapter plate 40. It is used to connect the slider unit 23 to the push rod 29 after the housing frame 22 has been slid into position beneath the outlet 12, and at the same time to fix the housing frame 22 to the vessel 10. 
     A bracket 33 is secured to the adapter plate 40, as best illustrated in FIG. 5. It may be secured to the adapter plate by any appropriate fastener, such as bolts. A coupling sleeve 34 is pivotally mounted in the bracket 33 for rotational movement above an axis parallel with the longitudinal direction of movement of the housing frame 22 on the guide tracks 52. The coupling sleeve 34 has an opening 35 therein which receives the push rod 29 therethrough. The coupling sleeve furthermore has an inner surface provided with dogs 36 or other appropriate detent members for engagement with the housing frame 22. The housing frame 22 has an end member 22&#39; that is connected to the end of the housing frame 22 and extends into the coupling sleeve 34, as illustrated in FIG. 1. Rotation of the coupling sleeve 34 is one direction allows the member 22&#39; to be inserted therein. Rotation in another direction causes the dogs 36 to engage corresponding notches in the member 22&#39; to longitudinally fix the member 22&#39;, and thus the housing frame 22, relative to the adapter plate 40. It is noted that the member 22&#39; can be separately fixed to the end of the longitudinal housing as shown in FIG. 1. The member 22&#39; further has an interior passage through which extends a connecting portion 23&#39;. The connecting portion 23&#39; is connected to the slider unit 23 and coupled to the push rod 29 by a ball 29&#39; on the front end of the push rod 29. 
     Referring now to FIGS. 2 and 3 in particular, the adapter plate 40, which is fastened to the vessel 10 by means of bolts or similar fasteners, has two L-shaped guide tracks 52 mounted thereon. The guide tracks 52 are parallel to one another, and each has an inner guideway 53 for supporting a respective support arm 55 projecting from a housing frame 22. 
     The two support arms 55, as can be best seen from FIG. 2, extend laterally from the two longitudinal sides of the housing frame 22. Mounted in the two support arms 55 are respective pluralities of spring packets, disposed one next to the other. Each spring packet comprises a guide peg 56&#39; and a plurality of plate springs 56 thereon. These can best be seen in FIG. 4, in which the lower surfaces of the guide pegs 56&#39;, also referenced as engaging surfaces, engage the guideway 53. The plate springs 56 produce an axial pressure on the guide pegs 56&#39;, thus pushing the housing frame 22 upwardly relative to the inner guideways 53. 
     In the illustrated state of the sliding gate valve assembly 20, the various plate springs 56 are under compression, producing a force in the upward direction in the housing frame 22. This force is transferred, as can be seen from the arrangement illustrated in FIG. 3, through the housing frame 22 to the slider unit 23 and the refractory plates 25 and 26. Consequently, this force is transmitted to the lower surface of the refractory head member 42 mounted in the adapter plate 40. By this pressure being exerted in the mounted position of the housing frame 22, it is ensured that no molten metal can leak out between the refractory plates 25 and 26 and between the head member 42 and the refractory base plate 25 when molten metal is poured through the outlet 12. 
     A manipulator 80 is illustrated in FIG. 6 and will be described in more detail hereinbelow. The housing frame 22 can be removed from the vessel 10 in the longitudinal direction of the guide tracks 53 with the manipulator 80 connected with the coupling peg 62. In order to release the housing frame 22 for the purpose of removing the housing frame 22, the coupling sleeve 34 first has to be rotated 90° with the manually operated lever 34&#39;, releasing the member 22&#39; and the connecting portion 23&#39;, and releasing the push rod 29 from the slider unit 23. The housing frame 22 is then movable to the left as seen in FIGS. 1 and 2. As soon as the support arms 55 are out of engagement with the guide tracks 52, the housing frame 22 can be removed from the vessel and taken to an assembly station remote from the hot converter. The refractory plates can then be replaced. 
     The interaction between the support arms 55 and the guide tracks 52 will now be discussed in more detail. As shown in FIG. 4, four spring packets, which are of the same dimensions and arranged in a row, are provided for each support arm 55. They are, furthermore, arranged in the support arms 55 so that they are all set with respect to one another in a stepped manner in order that the lower engagement surfaces of the guide pegs 56&#39; of the spring packets will define a line. This line extends parallel to an engagement surface 53&#34; of the guideway 53. The engagement surface 53&#34; extends at an angle relative to the planes of the refractory members, in particular, the plane perpendicular to the axes of the outlet 12, i.e. a plane parallel to the lower surface of the refractory head member 42, the surfaces of the refractory base plate 25 and the sliding surface of the refractory sliding plate 26. The angle is an acute angle of only about one to two degrees. Accordingly, when moving the housing frame 22 into the illustrated operational state, the spring packets 56 are stressed by the oblique arrangement of the engagement surfaces only shortly before the illustrated end position of the housing frame 22. For example, the spring packets 56 might only be stressed by the oblique arrangement of the engagement surfaces a distance corresponding to the distance between two spring packets before the housing frame reaches the end position, i.e. immediately before the end position. 
     The result of this arrangement is that the pressing of the upper slide plane surface 27 of the refractory base plate 25 against the lower end surface 43 of the refractory head member 42 is effected only over a short distance, close to the operational position. 
     The guideway 53 of the guide tracks 52 is further provided with an entry ramp 53&#39;. This ramp has a greater rate of inclination, making it easier to introduce the housing frame 22 into the guide tracks 52. 
     FIG. 5 illustrates more particularly the arrangement of the coupling sleeve 34. As discussed before, the coupling sleeve 34 has an opening 35 receiving the push rod 29 therethrough. The front end ball 29&#39; is provided with lateral flat members that are adapted to be introduced into a corresponding recess in the connecting portion 23&#39; of the slider unit 23. When the lever 34&#39; is directed downwardly, and the housing frame 22 is installed by moving the housing frame 22 to the operational position, the member 22&#39; on the end of the housing frame 22 moves into the coupling sleeve 34. The connecting portion 23&#39; correspondingly engages with the front end ball 29&#39; of the push rod 29. As soon as the housing frame 22 has been pushed into the end position, the coupling sleeve 34 is rotated by 90° by the lever 34&#39;. This also rotates the push rod 29 through 90°, causing the lateral flats of the push rods 29 to be engaged with the connecting portion 23&#39;. At the same time, the coupling sleeve 34 has the dogs or other engagement members thereof engaged with the corresponding notch or notches of the member 22&#39;. The lever 34&#39; can then be secured against rotation with a locking member 38 (for example a clamp) as shown in FIG. 2. From this position, the push rod 29 can operate the slider unit 23 through the coupling sleeve 34 and the member 22&#39;. The slider unit 23 is moved by a suitable drive element, such as a hydraulic drive. 
     The above sequence is reversed when it is desired to remove the housing frame 22. 
     As noted above, FIG. 6 shows a manipulator 80 according to the present invention. The manipulator 80 includes a manipulator support 86 that can be moved horizontally in any direction and that can be rotated about its axis, as illustrated by the arrows shown in the figure. A stacker truck 87, or similar device, is used to support the manipulator support 86. Illustrated is a fork of the stacker truck 87. The fork can be moved in any one of the directions shown in the figure, i.e. it can be pivoted, rotated, or moved up and down. 
     A control cabin 85 is mounted on the manipulator support 86. Connected with the control cabin 85 is an actuating cylinder 84. The manipulator support 86 further has vertically adjustable support legs 89 used to support the manipulator support on a platform 90 as appropriate and desired. 
     A gripper 88 is pivotally connected to the manipulator support 86. The gripper 88 is used to determine the position of the manipulator 80 relative to the molten metal vessel 10. This is done by moving the gripper 88 to engage centering pegs 83 provided on the adaptor plate 40, which pegs are for example illustrated in FIGS. 2 and 3. The pegs 83 are preferably provided on both sides of the plate 40. Accordingly, the manipulator 80 can determine the spatial position of the molten metal vessel 10 using the gripper 88 to engage the centering pegs 83. 
     The actuating cylinder 84 is pivoted about a horizontal axis through a rotary mounting 92 on the cabin 85. A cylinder unit 91 is used to pivot the actuating cylinder 84 about the horizontal axis. A piston rod 81 extends from the actuating cylinder 84, and has on its end a coupling socket 82. The coupling socket 82 is rotatable about its axis and can be moved over the coupling peg 62 on the housing frame 22 and be coupled to the coupling peg 62 by rotation. After the housing frame 22 has been coupled to the actuating cylinder 84 through the coupling peg 62 and the coupling socket 82, the housing frame 22 can be removed by axial movement of the piston rod 81. 
     The housing frame 22 is then taken to an assembly station for a replacement of the refractory components. The manipulator 80 is moved by the stacker truck 87 to a position as preferably shielded from heat and dirt. 
     While the present invention has been described above in connection with the preferred embodiment and a specific example, it should be emphasized that variations of the above features will occur to those skilled in the art. Such variations should be considered within the scope of the present invention. 
     For example, the spring packets that are integrated in the housing frame 22 along the support arms 55 of the housing frame could also be arranged in the guide tracks 52 through use of known tilting levers, whereby the tilting levers would define guideways 53. Furthermore, sliding gate valve assembly in accordance with the present invention is also basically suitable for use with discharge regulation of electric furnaces, a ladle used in continuous casting installations, and a distributor vessel.