Abstract:
The invention relates to a strip-casting machine for production of a metal strip, comprising two adjacent case-width casting rollers ( 22, 24 ), forming a casting gap ( 15′ ), with side seals ( 25 ) arranged on the front face thereof. The rotating casting rollers are mounted on a machine mount ( 32 ). Between the above and the side seals ( 25 ), the metal melt, introduced by means of at least one casting tube ( 13 ), or similar, is protected by at least one gaseous medium. At least said casting rollers ( 22, 24 ) are surrounded on at least the case width and front face thereof as well as the side seals by a preferably multi-component housing ( 30, 60, 80 ). An optimal sealing of the casting rollers as well as the metal strip and the metal strip appearing from between the rollers can thus be achieved in a simple manner.

Description:
BACKGROUND OF THE INVENTION 
   The invention pertains to a strip-casting machine for the production of a metal strip with two adjacent casting rolls with lateral surfaces of a certain width which form a casting gap between them, the end surfaces of the rolls being provided with side seals, the rolls being rotatably supported on a machine stand and driven by at least one motor, where the metal melt is supplied through at least one casting tube or the like to the area between the casting rolls and the side seals, and is protected by at least one gaseous medium. 
   In a strip-casting machine of the generic type in question according to the publication WO-A-97/34,718, the horizontally mounted casting rolls are supported in a machine frame, which carries the rolls; a distribution vessel rests on the frame. To seal off the surface of the metal bath, a plate is provided over the bath, approximately parallel to its surface, which seals off the two casting rolls. Underneath the casting rolls are separate wall parts, which adjoin the machine frame, and a multipart box, which is adjacent to the wall parts. The strip emerges from this box. The disadvantage of this strip-casting machine is the relatively complicated design used to seal off the metal bath and/or the metal strip produced. 
   In another known twin-roll strip-casting machine according to the publication EP-A-0 780 177, a box-like container is provided to seal off the solidified metal strip emerging underneath from the gap between the casting rolls. The walls of this container extend all the way to the bottom parts of the outer jackets of the casting rolls, where a seal is created by a sealing element. This type of seal, however, is relatively complicated in design and expensive to maintain and also entails undesirable contact between the sealing element and the rotating casting roll. When leaks occur, there is the danger that scale can form on the metal strip, which lowers the quality of the product. 
   SUMMARY OF THE INVENTION 
   Against this background, the present invention was based on the task of creating a strip-casting machine of the generic type indicated above, by means of which both the metal bath or the produced metal strip and the casting rolls can be sealed off satisfactorily from the ambient air and also so that the operation and maintenance of the machine can be simplified. 
   The task is accomplished according to the invention in that a preferably multipart housing encloses at least the lateral surfaces and ends of the casting rolls and the side seals. 
   With this design of the strip-casting machine according to the invention, it is easy to achieve an optimum seal for both the metal bath present between the rolls and the metal strip emerging underneath from between the casting rolls. 
   The casting rolls and the side seals, however, can nevertheless be made accessible quickly and easily for the purpose of repair and maintenance, as a result of which the output of the machine can be increased. 
   In a highly advantageous design, the housing for the metal strip emerging underneath from the casting gap between the casting rolls is adjoined by a longitudinal housing with a chamber, where the chamber formed by the housing is connected by an opening to the adjoining chamber of the longitudinal housing. 

   
     BRIEF DESCRIPTION OF THE DRAWING 
     Exemplary embodiments of the invention and additional advantages offered by it are explained in greater detail below on the basis of the drawing: 
       FIG. 1  shows a schematic longitudinal section through a strip-casting machine according to the invention; 
       FIG. 2  shows a cross section of a housing along the axes of the casting rolls of a strip-casting machine according to the invention; 
       FIG. 3  shows a cross section through the housing according to  FIG. 2 ; and 
       FIG. 4  shows a schematic view of another variant of a strip-casting machine. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1  shows a strip-casting machine  20  for the production of a metal strip  15 , especially a steel strip, which can be produced in a continuous casting process. This strip-casting machine  20  is mounted on a stage  12  and is supplied with metal melt  16  from a distribution vessel  18  installed above the machine, as is known from conventional continuous casting systems. It is advisable for the distribution vessel  18  to have a pouring opening  17 , which can be closed by a stopper  19  or the like, and a casting tube  13 , extending to a point between the casting rolls  22 ,  24 , through which the melt can flow out. 
   The main components of this strip-casting machine  20  are the two essentially parallel casting rolls  22 ,  24 , the axes of which are approximately horizontal. A side seal  25  is provided at each end of the rolls, as a result of which an opening is formed, which is closed on all sides and which has the casting gap  15 ′ at the bottom. Each of the casting rolls  22 ,  24  is supported rotatably at each end on a machine stand  32  and is driven by a motor integrated into the stand. 
   According to the invention, the casting rolls  22 ,  24  are surrounded by a closable housing  30 , which has an opening  30 ′ in the top for the casting tube  13 , which projects into the area between the casting rolls  22 ,  24 , and an opening  30 ″ in the bottom for the emerging metal strip  15 . These openings  30 ′,  30 ″ are sealed, and the chamber  33  inside the housing is filled with a shielding gas, preferably an inert gas, during the casting operation. In cases where two or more casting tubes are used, it would be possible for several openings  30 ′ to be provided in the top. These openings could be round or slot-shaped, and there does not necessarily have to be a casting tube in each one. 
   It is highly advantageous for this box-shaped housing  30  to be a certain distance away from the sides and the top of the casting rolls  22 ,  24  or from the machine stand  32 , so that there is no need for the sealing elements required in the case of the casting machine according to the previously cited publication EP-A-0 780 177 to seal the metal melt off from the outside. 
   In the top, this housing  30  is provided with two horizontal doors  35 , which are designed so that they can be slid horizontally from the closed position shown in  FIG. 1  into an open position. For this purpose, they are guided laterally in appropriate rails (not shown), and it is advantageous for them to be lowered into the closed position shown so that the housing  30  can be sealed in the desired manner. 
   It would also be possible, however, to provide only one door, which would in any case reduce the number of gaps to be sealed. It would be advantageous for this one door to be approximately equal in size to the two doors  35  shown and to be provided with an appropriate opening  30 ′ for the passage of melt. 
   In addition, the housing  30  is also provided with openings  39 , which can be closed by doors  36 . These openings make it possible for the side seals  25  of the casting rolls  22 ,  24  to be guided by manipulators  40 , which are free to travel outside the housing  30  and which are thus able to remove the side seals from their operating positions shown and to take them out through these openings  39  and return them to the housing  30  again. The manipulator  40  in question has for this purpose a support arm  41  and a drive  42 , which can adjust the height of the arm. The manipulator can thus be moved from an operating position to a retracted maintenance position and back again. In the operating position of the manipulator  40 , the unsealed opening  39  can be sealed off by means of a separate shield enclosure  38 . This shield enclosure  38  surrounds the manipulator  40  and rests tightly against the side of the housing  30 . Cassettes are used to bring the side seals up into position and to carry them away. 
   Another advantage obtained within the scope of the invention is that the cast metal strip  15  is guided underneath the housing  30  into an additional longitudinal housing  44 , which forms a chamber  45 , in which a shielding gas is also present in order to protect the metal strip  15  from contact with oxygen and especially to prevent the formation of scale. In this chamber  44 , several rollers  46  and compression rolls  47  are installed, so that the metal strip  15  is guided through this longitudinal housing  44  and through a sealed opening  48  in one end of the housing. After it emerges from the housing  44 , the metal strip, which has cooled by this point, can be coiled up, for example, or sent on for further processing. 
   In addition, the longitudinal housing  44  has a pit  49  underneath the opening  30 ″ and thus underneath the casting gap  15 ′. A collecting tank  52  is provided in this pit in the plant floor  51 . This collecting tank  52  has the task of collecting any liquid metal which might escape from between the casting rolls in the event of a leak and thus of preventing any damage from occurring. Above this tank  52  are also swinging guide flaps  54 ,  55 , which form a pass-through opening in the position shown, whereas in the pivoted position  54 ′,  55 ′ they form a guide path for the metal strip  15 . 
   In the state of the casting operation illustrated in  FIG. 1 , the top opening  30 ′ in the housing  30  is sealed off by a bellows  11  or the like, which connects the housing to the vessel  18 . The sleeve-like bellows  11  surrounds the casting tube  13 . The casting tube could also be omitted and the melt simply allowed to fall freely. The lower opening  30 ″ in the housing, through which the strip  15  passes, can be sealed off by a sealing device in the form of a gas shield, for example, produced by nozzles  34 . In principle, however, this sealing device could also be omitted, and the opening  30 ″ thus could lead directly to the chamber  45 . 
   In addition, the housing  30  has a feed line (not shown) for the injection of a shielding gas into the interior space  33 . Shielding gas can also be supplied to the distribution vessel  18 , which is provided with a cover. The gas introduced into the housing  30  can be cooled and returned through a gas circuit. Upon completion of the casting operation and before the housing is opened, the shielding gas can be pumped out and into a storage tank, and the air in it can be filtered out if desired. 
     FIGS. 2 and 3  show the principle of a variant of a strip-casting machine, which is designed basically in the same way as the machine according to  FIG. 1 . In this strip-casting machine, a housing  60  is provided, which, according to the invention, surrounds the casting rolls  22 ,  24 . The multipart housing  60  extends around both the lateral surfaces and the ends of the rolls and thus also encloses the side seals  62 . The motor stands  61  supporting the axles  64  of the casting rolls  22 ,  24 , however, are not enclosed. The housing  60  surrounds the axles at both ends of the casting rolls and also the drive  66  of the seals  62 . At the top, it is a certain distance away from the indicated melt distribution vessel  18 . 
   The multipart housing  60  is provided with a base  67  where it meets the longitudinal housing  65 ; the base can be attached by fastening elements  69  to the longitudinal housing. 
   Between the housing  60  and the longitudinal housing  65 , an opening  70  is present, which connects these two housings  60 ,  65  to each other. The longitudinal housing  65  is advantageously sealed all the way around and has only one sealed outlet for the cast metal strip  15 . 
     FIG. 4  shows a strip-casting machine according to the invention, again with two casting rolls  22 ,  24 , which are contained in a housing  80 . This housing  80  consists of double side walls  81  and a cover  82 , which is supported so that it can be lifted off, as indicated by the cover  82 ′, which has been removed. 
   Within the scope of the invention, the housing  80  surrounds the casting rolls  22 ,  24  and the side seals  83 . In addition, the housing has an opening  84  at the bottom, which communicates with the chamber  85 ′ of a longitudinal housing  85 . The housing  80  is positioned in a frame stand  88 , which has wheels  87 , which are guided on rails  89 . 
   It is advantageous, furthermore, for both the housing  80  and the longitudinal housing  85  to be water-cooled, so that their temperature does not increase excessively during continuous operation. 
   With this strip-casting machine according to  FIG. 4 , a design which is independent of format has been created, because the housing can be made larger or smaller, depending on the diameter of the casting rolls.