Patent Publication Number: US-3877621-A

Title: Sliding plug for a molten metal container

Description:
United States Patent Seybold Apr. 15, 1975 SLIDING PLUG FOR A MOLTEN METAL [56] References Cited CONTAINER UNITED STATES PATENTS [75] inventor: Rolf Seybold, Solingen, Germany 2,863,189 12/1958 Beck 222/559 UX 3,354,939 11/1967 Caldern 222/559 UX [73] Ass&#39;gneei Evert! Germany 3,574,341 12/1968 Fehling et a]. 2 222/559 ux [22] Filed: Oct. 17, 1973 Primary ExaminerRobert B. Reeves [211 App! 407381 Assistant ExaminerDavid A. Scherbel [30] Foreign Application Priority Data 57 ABSTRACT Germany 2251484 A plug device for a container for molten metals having a refractory movable closure which can open and [52] US. Cl i, 222/559; 25l/l44 Close a fl path, d which in its open position pen [5 l Ilit. Cl BZZCI 37/00 mits fl of metal i 3 Chamber which i normally f [58] new of Search 222/559 greater cross-section that that of the flow path.  
 222/DIG. 13, 461; 25l/l44; 164/335 10 Claims, 3 Drawing Figures r i K/&#39; SLlDING PLUG FOR A MOLTEN METAL CONTAINER The invention relates to a sliding plug for casting ladles or for similar vessels. from which molten metals. particularly steel. are discharged through a bottom oritice. comprising a guide which is fitted on the base of the ladle from the outside. and a refractory sliding part which is capable of moving relative to the guide between a position closing the bottom orifice and one which opens it.  
  Sliding plugs of this kind are frequently used instead of other closing devices. which consist essentiaily of a stopper rod which is introduced from above into the molten metal. and closes or opens the bottom orifice. Unfortunately this known arrangement presents substantial problems which are mainly due to the fact that the stopper rod cannot be operated reliably enough at the very high temperature of the liquid metal. How  
 ever. on the other hand. casting by means of a stopper rod has advantages. amongst which in particular. control of the flow rate by varying adjustment. is worthy of mention, which is not normally possible with the conventional sliding plug. Sliding plugs can normally only be operated so as to be fully open or closed; in any intermediate position. the opening edge of the sliding plug would be subjected to excessive wear. and finally lead to scaling difficulties A further disadvantage of the conventional sliding plug is that very large mechan ical forces are needed for its operation. over a relatively long distance of travel. Along this travel. the refractory lining of the sliding plug is also subjected to considerable wear. The fact that the sliding plug can only be operated into its fully open position. causes the molten metal to be discharged at a very high speed. particularly at the start of the casting process. due to the substantial static pressure. which can damage moulds by erosion and the like.  
  On this basis. the objective ofthe invention is the design of a sliding plug of the type described above. such that on the one hand it has the advantages of the controllability of a plug operated with a stopper rod. and on the other hand. it has the accessibility of a sliding plug which is operable from the outside. In accordance with the invention. this is achieved in that the sliding part is connected to the refractory sealing cone or a corresponding sealing body. particularly of rotationally symmetrical shape. and that it is movable in a vertical direction. where the sealing cone in the lowered closing position. abuts with its peripheral surface on a compltr mentary surface or matching edge. and in its raised opening position. permits the flow of metal into a clos ing chamber formed by the guide or sliding part. the cross-section of this closing chamber normally being greater than the flow cross-section adjustable by the seal. and from which the metal is discharged through a bottom orifice.  
  A sliding plug designed in this manner has the advantage that it can be controlled within wide limits. for which purpose its sliding part is moved vertically. Dur ing this. the bottom orifice is not subjected to the full static pressure of the molten metal in the casting ladle or similar vessel. but only to the static pressure of the metal in the closing chamber. The closing chamber drains completely after closure ofthe bottom orifice. as sufficient space can be left for air to enter. between the said chamber and the guide. In this area. an annular gap is produced. which has the additional advantage that if the sealing cone should be damaged and allow too much molten metal to be discharged. this molten metal would solidify in the annular gap. and block the hole. For the controllability it is particularly advantageous that not only is a short adjusting path sufficient. but that for this purpose. only very low mechanical forces are needed. A further element of safety is achieved in that if the actuating device fails. automatic closing takes place. as the sealing cone then drops down. and its wall acts as a seal. This behaviour of the sealing cone can also be utilised as a rapid shut-off. where some kind of component is built in. which can be withdrawn. so that the entire assembly drops. down. and brings the sealing cone into its sealing position.  
  The complementary surface of the bottom orifice matching the peripheral surface ofthe sealing cone. advantageously has the shape of an annular block. which is inserted into the bottom orifice which corresponds to its dimensions. and is held in place by a plate supporting it. fixed on the bottom of the ladle.  
  The invention provides design forms which differ from one another depending on whether the closing chamber is made from the guide or the sliding part. In the event ofthe closing chamber being formed from the sliding part. an open pipe section which extends downwards from the bottom the ladle acts as a guide. in which the sliding part which contains the closing chamber. is adjustable with lateral play. The lateral play here produces the annular gap through which the air can cnter. Naturally. a protective gas can also be fed in at this point.  
  In the alternative case of the closing chamber being formed from the guide. the said guide is conveniently made up or a refractory-lined cylinder containing the closing chamber. where this cylinder is linked with the base of the ladle and is completely enclosed with the exception of the bottom outlet andof an inner pipe sleeve extending vertically upwards. The sliding part is here capable of sliding with lateral play within the pipe sleeve. and is designed as a block carrying the sealing cone. and covering the pipe sleeve with an annular collar. Both the pipe sleeve and the collar are provided with an outer or inner flange such that both flanges. in an upper limiting position of the sealing cone. are in sealing contact with one another i.e.. create a seal.  
  in all cases. the sliding part is provided with a supporting member extending along the axis ofthe bottom orifice. the said extension making vertical movement of the sliding part possible.  
  The high accuracy of dosing which can be achieved with the new sliding plug. allows the sliding part to be included as a controlling member in a control circuit. In particular. the sliding part can be supported by a spring which is adjustable to different forces, such that the spring tries to press the sliding part upwards. but is prevented from doing so by the higher or lower level to which the closing chamber is filled. so that a state of equilibrium results, depending on the adjustment of the spring. Hence the flow rate can easily be maintained at a predetermined. adjust-able nominal value For further illustration of the invention. we refer to drawings of design examples. In these:  
 FIG. 1 shows a cross-section of the new sliding plug.  
  FIG. 2 shows an elevation. partially in section. corresponding to FIG. i. and  
  FIG. 3 shows a cross-section through a modified design form of the invention.  
  FIG. I shows first of all a partial illustration of the bottom. marked 1. of a casting ladle or similar vessel. The vessel has been lined in the conventional manner. with refractory brickwork. The bottom orifice 2 can be seen. the surround 3 of which. is made of refractory brickwork with a particularly high degree of resistance. Following completion of the ladle bottom. sealing cone 5 and annular block 4 were inserted from underneath. and plate 6. together with the pipe section 7 serving as guide. were screwed on in such a manner that plate 6 holds annular block 4 in position. The sealing cone 5 is designed with an anchoring facility 8. the upper end of which. as can he seen from FIG. I. expands. while the lower end is threaded.  
  The sliding part 9. with closing chamber 10. is movable inside pipe sleeve 7. The closing chamber has an annular shape. and is arranged in the refractory in sert ll of sliding part 9. The lower section of anchoring 8 passes through sliding part 9. and is held on the base of the sliding part by means of nut 12. In this manner the sealing cone 5 is linked with sliding part 9.  
  ln addition. bottom orifice [3 can be seen. again made from a special refractory insert 14. which expands conically upwards. and is inserted into the conical mantle tube 15. The annular gap between pipe section 7 and sliding part 9 makes possible not only completely unimpeded vertical movement of the sliding part. but also permits the entry of air. so that the closing chamber 10 can be drained completely. In addition. in the event ofdamage to the sealing cone 5. the molten metal can solidify in the said annular gap. so that the sliding part 9 is then blocked. and all the molten metal can be discharged correctly through the bottom orifice 13. A cam l6 presses against the end of the anchoring 8. this cam being located on the actuating shaft 17. which itself can be actuated with the aid of the handwheel 18. as can be seen from FIG. 2. FIG. 2 in addition. illustrates lateral telescopic guides l9 and 20. The sliding part 9 can also be moved by other actuators. such as for example. hydraulic. pneumatic or electromechanical drives. This is particularly relevant if the sliding part 9 is to be designed as controlling element in a control circuit. or is to be controlled in relation to. for instance. the level of molten metal in the casting ladle or in a mould.  
  FIG. 3 again illustrates the sealing cone 5 inserted in an annular block 4. Here. the sliding part is designed as block 24 which carries the sealing cone 5. and has an annular collar 26. To the ladle bottom. a cylinder 21 is connected. which is closed save for bottom orifice [3 at the base. and for an inner pipe sleeve 25 extending upwards. This cylinder 21 forms the closing chamber 10. which is also ringshaped. At the same time. the pipe section 25 forms the guide for the sliding part. The latter can be pressurised at its lower end by means which are not shown in this illustraton. in such a manner that adjustment of height is possible. by which the sealing cone 5 is either raised or lowered. and thus allows the desired quantity of molten metal to be discharged into the closing chamber 10. from which it is discharged through bottom outlet 13. Pipe section 25 can have an additional upper outer flange 22. while col lar 26 of the sliding part can have a lower inner llange 23. so that the two flanges come into sealing contact with one another when the sealing cone 5 is in the upper limiting position. Here we are again dealing with a sea] as in the design form according to FIGS. l and 2. which also becomes effective when sealing cone 5 fails. In this event. the sliding part which is made of refractory material. is forced upwards by the buoyancy forces. so that the closing chamber fills up completely. without the metal being able to flow out of any opening other than the bottom orifice 13.  
  The feature present in all design forms of the invention. by which the closing chamber has a cross-section which is normally greater than the flow cross-section which is adjustable with the sealing cone. is to be interpreted such that it may even be possible in exceptional cases. to create a flow cross-section which can exceed that of the closing chamber. by means of operating the sliding part into the extreme position.  
  In the design form in accordance with FIG. 2. additional telescopic guides 19 and 20 have been illustrated. Additional guides of this or another design. allow the movement of the sliding part in all design forms of the invention. to be so precise that a uniform annular gap is left free in relation to the other guide.  
 What l claim is:  
  l. A plug for a casting ladle having a surface defining a bottom orifice. said plug comprising a guide which is mounted on the exterior of the base of the ladle. a refractory part which is movably mounted on the ladle for movement relative to the guide between a first position closing said bottom orifice and a second position opening said bottom orifice. a refractory sealing body. said refractory part being connected to said refractory sealing body and being movable in a substantially verti cal direction. said sealing body being arranged so that in the first closing position its peripheral surface sealingly engages said surface on the ladle defining said bottom orifice and in the second opening position it permits the flow of metal through said bottom orifice. and a closing chamber formed in said plug. the crosssection of said closing chamber being greater than the cross-section of said bottom orifice. said closing chamber having an exit orifice in the bottom portion thereof which is laterally offset from said bottom orifice.  
  2. A sliding plug in accordance with claim I. wherein the ladle surface which is complementary to the peripheral surface ofthe sealing body is defined by an annular block which is mounted on the bottom of the ladle. and a supporting plate fixed on the ladle bottom for supporting said annular block.  
  3. A sliding plug in accordance with claim 1. wherein the guide is an open pipe section extending downwardly from the ladle bottom. and the refractory part contains the closing chamber and is movable within said guide. said part being spaced from said guide to provide a small gap therebetween so that said closing chamber is in communication with the surrounding atmosphere through said gap.  
  4. A sliding plug in accordance with claim 3., wherein an additional guide is provided to enable movement of the refractory part without substantial variation of said gap.  
  5. A sliding plug in accordance with claim I. wherein the guide is a refractory-lined housing containing the closing chamber and exit orifice. said housing being connected to the base of the ladle and having an inner open pipe sleeve extending vertically upwardly therein. said housing being completely enclosed with the excep tion of said exit orifice and said inner pipe sleeve. and  
  5 wherein said sliding part is a refractory block having its lower portion movably disposed within the pipe sleeve. said block carrying the sealing body and having an annular collar enclosing the upper portion of the pipe sleeve.  
  6. A sliding plug in accordance with claim 5. wherein said pipe section has an upper outer flange and said collar has a lower inner flange such that both of said flanges, in an upper limiting position of the sealing body. are in sealing contact with one another.  
  7. A sliding plug according to claim 5 wherein the lower portion of said block is spaced from said pipe sleeve to provide a small gap lherebetween so that the closing chamber is in communication with the surrounding atmosphere through said gap.  
  8. A sliding plug in accordance with claim I, wherein the refractory part has a supporting member extending along the axis of the bottom orifice. by means of which substantially vertical movement of the part is made possible.  
  9. A sliding plug according to claim I wherein the refractory sealing body is of rotationally symmetrical shape.  
  10. A sliding plug according to claim 9. wherein the refractory sealing body has a frustoconical portion.