Abstract:
A casting/rolling installation for producing hot-rolled strip. In order to save investment costs for the roll changing device in a corresponding installation with two parallel casting lines, without a roll change taking place in the process in a less operationally reliable and more complicated manner, the roll changing device is configured in the form of a rotary table and arranged in the intermediate space between the two casting lines.

Description:
The present application is a 371 of International application PCT/EP2014/050178, filed Jan. 8, 2014, which claims priority of DE 10 2013 224 633.1, filed Nov. 29, 2013, and DE 10 2013 200 438.9, filed Jan. 14, 2013, the priority of these applications is hereby claimed and these applications are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     The invention pertains to a casting/rolling installation for producing hot-rolled strip. In addition, the invention pertains to a method for removing and installing rolls in a reducing stand of the casting/rolling installation. 
     Casting/rolling installations for casting and rolling metal strip are generally known from the prior art. A known type of such a casting/rolling installation is, for example, the so-called “compact strip production” installation. This known type of installation is shown in  FIG. 4  and is described below in schematic terms. Additional types of installations are also possible, which means that the example is not to be understood as limiting in any way. 
       FIG. 4  shows a single-strand casting/rolling installation  100 . In it, liquid metal, typically liquid steel, is transported in a tundish  180  by means of a casting bay crane  190  to a distributor device  120 , typically a so-called swiveling tundish. From the distributor device  120 , the liquid steel is conducted into a first mold  112 - 1 , where it solidifies on the cooled edges of the mold, as a result of which a strand shell is formed. At the outlet of the mold  112 - 1 , the cast strand, which is still liquid on the inside, is sent to a downline roller apron  114 - 1 , which deflects the cast strand emerging vertically from the mold  112 - 1  into a horizontal plane. As it is being guided along the roller apron  114 - 1 , the cast strand is cooled further until it has completely solidified. After its complete solidification, the cast strand  210 - 1  passes through a first reducing stand  116 - 1 , which rolls the cast strand and thus reduces its thickness. Seen in the casting direction R, the cast strand then passes through a shears  192 , which cuts the strand into slabs  220 - 1 . The shears  192  are typically assigned a scrap box  193  for carrying away the metal scrap which accumulates during the cutting of the cast strand. The shears are also typically followed by a tunnel furnace  194  to hold the slabs at temperature or to increase the temperature of the slabs slightly to the slab rolling temperature required by the following finishing line  195 . In the finishing line, the slabs are rolled out into hot-rolled strip  230 - 1 . Downstream from the finishing line  195 , a cooling section  196  and a reel device  197  are typically provided, the latter being used to wind up the cooled hot-rolled strip. 
     In addition to the single-strand installation just described with reference to  FIG. 4 , multi-strand installations are also known, in which several of the strands shown in  FIG. 4  are arranged parallel to each other. 
     The casting/rolling installation just described with reference to  FIG. 4  takes advantage of the heat of casting, which significantly decreases the need to reheat the slabs in the tunnel furnace  194  in comparison with the method of supplying slabs which have already cooled. 
     For metallurgical reasons, it is favorable to achieve a degree of deformation of the cast strand  210 - 1  of at least 60-80% from the outlet of the roller apron to the reel device  197 , where the hot strip is coiled up. During the production of the thicker grades of hot-rolled strip, slab thicknesses in the range of 40-120 mm are reached. In the case of thicker slabs or thicker hot-rolled strip, it is advantageous for the deformation process to be conducted in several stages. For this purpose, the cast strand is subjected in the previously mentioned reducing stand  116 - 1  to a first deformation step as soon as it leaves the roller apron  114 - 1  and thus brought to a thickness which is suitable for the following compact finishing line  195 , where the slabs are brought to their final, desired thickness. 
     From an energy standpoint, it is logical to conduct the first deformation step immediately after casting. To realize this, the first reducing stand  116 - 1  is set up directly behind the outlet of the roller apron  114 - 1  and thus under the casting platform  118 - 1  of the casting/rolling installations  100 . The casting platform, as shown in  FIG. 4 , is typically set up as a horizontal work platform at the level of the mold  112 - 1 . On the casting platform, teams of operators must perform maintenance jobs in particular on the distribution device  120 , and tools and consumable materials are also stored on the casting platform. For reasons of occupational safety, the casting platform is configured as a closed but easily walkable work zone. The entire casting installation is operated by one person from a control stand  198 , which, as shown by way of example in  FIG. 4 , is arranged above the casting platform. 
     The arrangement of the first reducing stand  116 - 1  directly after the roller apron and underneath the casting platform  118 - 1  just described as being advantageous with respect to energy use suffers from the disadvantage that the casting bay crane  190  traveling above the casting platform  118 - 1  cannot access the reducing stand  116 - 1 . In particular, the casting bay crane  190  therefore cannot be used to change the rolls  310 ,  320 - 1 ,  320 - 2  of the reducing stand  116 - 1 . This is also true for the reason that the operator in the control. stand  198 , from which the movement of the casting bay crane  190  is controlled, has no view of the area where the reducing stand  116 - 1  is installed, because this view is blocked by the casting platform  118 - 1 . 
     It must also be taken into account that the operating teams on the casting platform and the operating teams underneath the casting platform in the area of the outlet from the roller apron typically have neither visual nor spoken contact with each other, so that work being carried out in parallel by the two teams can lead under certain circumstances to hazardous situations. 
     One possible way of changing the rolls in the reducing stand  116 - 1  underneath the casting platform  118 - 1  could consist in providing a separate crane underneath the casting platform. Such a crane, however, would require considerable investment, and in addition the height of the installation or of the casting platform may not always be sufficient to allow the crane to be operated there usefully. The need to elevate the casting platform in these cases would also necessarily be associated with considerable cost. 
     In the prior art, there is a wide variety of known roll-changing devices for removing and carrying away worn-out rolls from a reducing stand and for bringing up and installing new rolls in the stand. Among others, roll-changing devices in the form of a turntables are also known. Such turntables are known specifically from, for example, German Offenlegungsschrift No. DE 1 527 622; German Patent No. 851941; and Patent DE 693 224, published by the Patent Office of the German Reich. The last-mentioned patent discloses a rotating table, which can be turned by a drive. A track for accepting sets of rolls is arranged on the turntable. At the periphery of the turntable, there is typically an intermediate holding station for the rolls, which comprises track spurs, arranged in a star-like manner, connecting to the track on the turntable. A device is provided on the turntable to push a set of rolls from the intermediate holding station onto or up to the turntable and vice versa to push a set of rolls off the turntable and onto the holding station. The track spurs on the holding station allow individual rolls or a complete set of rolls, after they have been removed from the roll stand, to be deposited on a track spur and for a second set to be moved into position immediately in the roll stand without the need for a crane. The same device, which can be operated hydraulically, for example, is also adapted to bring new rolls into position opposite the roll stand and then to push the rolls into the stand and vice versa to pull worn-out rolls back out of the stand. 
     U.S. Pat. No. 1,833,376, furthermore, discloses a roll-changing device in the form of a turntable, which can be locked in certain rotational positions and thus prevented from rotating further. 
     SUMMARY OF THE INVENTION 
     Against the background of this prior art, the invention is based on the goal of improving a known casting/rolling installation and known methods for removing and installing rolls in the rolling stands of these installations in such a way that the investment costs for a roll-changing device for changing the rolls are reduced, whereas, at the same time, a roll change can be carried out easily and reliably, in particular in the case of a reducing stand downline from the roller apron. 
     This goal is achieved, in the case of a casting/rolling installation with a first casting line and, parallel to that, a second casting line, in that the first and second reducing stands are set up in such a way that their operating sides are located in the intermediate space between the two casting lines, and in that the roll-changing device is configured in the form of a turntable and is arranged in the intermediate space between the two casting lines at the level of and between the two reducing stands. 
     The claimed turntable between the first and second casting lines offers the advantage that, thanks to its presence, only one roll-changing device is needed to change the rolls of both reducing stands of the casting lines. It is thus no longer necessary to provide separate roll-changing devices, one for each rolling stand, in particular for each reducing stand. This decreases the investment costs. A roll change can be carried out by means of the turntable easily and reliably; in particular, changing the rolls in this way has no effect on the work being carried out on the casting platform. 
     The term “operating side” of a rolling stand refers to the side of the rolling stand, transverse to the rolling direction, on which in particular the roll changes are performed. The opposite side of the rolling stand is called the “drive side”; on this side, the drives for the rolls, i.e., motors, gearboxes, and drive spindles, are typically arranged, for which reason these drive sides are typically inaccessible and in particular are not suitable for a roll-changing operation. 
     The term “backup roll” in the present description means not only the actual backup rolls themselves but possibly also any intermediate rolls which may be present in six-high stands. The phrase “additional rolls” also used here can mean in particular the actual backup rolls or intermediate rolls. 
     According to a first exemplary embodiment, the casting/rolling installation according to the invention comprises a casting bay, in which, among other things, the molds, the roller aprons, the reducing stands of the two casting lines, and a casting bay crane are arranged; the installation also comprises, next to the casting bay, an adjacent bay, connected to the casting bay in the casting direction, which also comprises a crane. The adjacent bay can be for example, a furnace bay or a rolling bay. 
     For the arrangement of the turntable between the two casting lines, there are in principle three possible variants. According to a first variant, the turntable can be located between the two casting lines in such a way that at least a partial area of the turntable is accessible to the casting bay crane or to the crane of the adjacent bay. Alternatively, the turntable can be completely covered or roofed by, for example, the casting platform, so that neither the casting bay crane nor the crane of the adjacent bay can access the turntable. In the case of this second variant, it is therefore necessary to provide an intermediate holding station for the rolls of the first and second reducing stands in the adjacent bay between the two casting lines and—looking in the casting direction—downstream from the turntable, preferably directly at its periphery. In contrast to the turntable, the intermediate holding station is not roofed, in particular not covered by the casting platform; on the contrary, because of the way it is arranged in the adjacent bay, it is accessible to the crane of the adjacent bay. In concrete terms, the crane of the adjacent bay thus serves to deliver new rolls to the intermediate holding station and to carry away the worn-out rolls from the holding station. According to a third variant, a combination of the two first-mentioned variants is also possible, according to which a partial area of the turntable is accessible either to the casting bay crane or to the crane in the adjacent bay, and in addition the intermediate holding station is accessible to the crane in the adjacent bay. 
     The turntable is stationary; that is, it cannot be moved in a translational manner. Its rotational axis remains permanently in place. 
     It is advantageous for the first and second reducing stands to be on the same level as the first and second casting lines, so that the vertical center planes of the two stands coincide. The turntable is then preferably arranged between the two casting lines in such a way that its stationary vertical rotational axis lies in the coinciding center planes of the first and second reducing stands. It is then possible for the turntable to serve the reducing stands in both casting lines in the same way. 
     The radius of the turntable is advantageously configured in such a way that the periphery of the turntable reaches all the way to the first and second reducing stands, namely, to the operating sides of each stand. This offers the advantage that there is no need to bridge a gap between the turntable and the rolling stands. The first reducing stand is advantageously directly downstream, with respect to the casting direction, from the outlet of the first roller apron, and the second reducing stand is advantageously also directly downstream, with respect to the casting direction, from the outlet of the second roller apron. As a result of this close arrangement of the reducing stands at the outlets of the roller aprons, it is guaranteed that, for this purpose of reducing the thickness of the cast strand, optimal use can be made of the casting heat of the cast strand. To this extent, this arrangement serves as a way of reducing energy consumption. 
     A pulling and pushing device, e.g., in the form of a roll-changing locomotive or a hydraulic cylinder, is preferably provided on the turntable. The pushing and pulling device serves to pull the rolls out of the first and/or second reducing stand and onto the turntable, to push the rolls from the turntable into the first and/or second reducing stand, or to move or transfer the rolls between the turntable and the intermediate holding station. 
     Providing an opening in the area of the rotational axis of the turntable or providing a vertically oriented tubular configuration in the area of the rotational axis offers the advantage that power or media lines can be passed from the floor or foundation of the casting/rolling installation to the pushing and pulling device on the turntable. 
     The turntable advantageously comprises an upper level with positions for receiving the work rolls, for example, and a lower level with positions for receiving additional rolls, e.g., the backup rolls, from at least one of the two reducing stands of the two casting lines. This configuration offers the advantage that not only individual rolls but also entire sets of rolls, possibly together with a roll-change stand, can find room simultaneously on the turntable. 
     In principle, each of the two casting lines can comprise its own casting platform, wherein it is also conceivable that an intermediate space between the two casting platforms could be present above the intermediate space between the two casting lines. Into this intermediate space, it would be possible, for example, to drive the casting bay crane so that it can access at least partial areas of the turntable. It is also possible to combine the two casting platforms into common casting platform, which then also extends transversely to the casting direction and spans the gap between the two casting lines. The casting lines are each configured as casting/rolling installations, as described above by way of example in the form of “compact strip production” installations in the introduction with reference to  FIG. 4 . 
     The goal of the invention described above is also achieved by the methods for removing rolls from, and installing rolls in, the reducing stands of the casting/rolling installation according to the invention. The advantages of these methods correspond to the advantages cited above with reference to the claimed casting/rolling installation. 
    
    
     
       Four figures in all are attached to the description, wherein: 
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  shows a longitudinal cross section through the turntable between two lines of the casting/rolling installation according to the invention, with a view toward a casting line; 
         FIG. 2  shows a top view of the casting/rolling installation according to the invention with first and second casting lines (other possible casting lines are not shown); 
         FIG. 3  shows a cross section through the casting/rolling installation according to the invention at the level of the center planes of the two reducing stands; and 
         FIG. 4  shows a casting/rolling installation according to the prior art. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention is described in detail below in the form of exemplary embodiments with reference to figures cited above. The same technical elements are designated by the same reference numbers in all of the figures. 
       FIG. 1  shows a longitudinal cross section through the casting/rolling installation  100  according to the invention. It is a part of the general casting/rolling installation previously described with reference to  FIG. 4 , but supplemented by the turntable  130  according to the invention. Specifically,  FIG. 1  shows a casting bay  138 , to which, seen in the casting direction R, an adjacent bay  140  is connected. The boundary between the two bays coincides in  FIG. 1  with the outer edge of the first casting platform  118 - 1 ; this boundary is indicated in  FIG. 1  by the reference number  139 . On the casting platform, the tundish device  120  in the form of a movable distributor can be seen. On the left edge of the figure, furthermore, the tail of a roller apron  114 - 1  can be seen, downline from which, in the casting direction R, a first reducing stand  116 - 1  is located. Downstream in turn from the reducing stand is a device  145  for removing the cold strand. This cold strand-removing device  145 , as shown in  FIG. 1 , is also located, like the first roller apron  114 - 1  and the first reducing stand  116 - 1 , underneath the first casting platform  118 - 1 . All these devices are therefore inaccessible to a casting bay crane, which is typically located above the casting platform. Again looking in the casting direction we can see, downstream from the cold strand-removal device, the shears  192  and a tunnel furnace  194  in the adjacent bay  140 . The shears  192  are provided with a scrap box  193 .  FIG. 1  also shows, in longitudinal cross section, the roll-changing device according to the invention in the form of a turntable  130 . Its stationary rotational axis  134  preferably coincides, as shown in  FIG. 1 , with the vertical center plane M 1  of the first reducing stand  116 - 1 . It is also possible to see that the turntable is held and rotatably supported by a turntable bearing  129  on a foundation  126 . The rotational movement of the turntable  130  around its vertical rotational axis  134  is accomplished by means of a turntable drive  127 . Locking devices or indexing devices  128  are provided to lock the turntable  130  in predetermined rotational positions. 
       FIG. 2  shows a top view of the casting/rolling system  100 . The first casting line  110 - 1  and, parallel to that, a second casting line  110 - 2  can be seen. The casting lines are spaced a certain distance apart. The casting direction R proceeds in  FIG. 2  from right to left. The first mold  112 - 1 , the first roller apron  114 - 1 , the first reducing stand  116 - 1 , the first shears  192 - 1 , and the first tunnel furnace  194 - 1  of the first casting line  110 - 1  are shown schematically. In the first shears  192 - 1 , the incoming cast strand  210 - 1  is cut into slabs  220 - 1 . The parallel second casting line  110 - 2  is built analogously with like components being indicated with the same reference numerals followed by “- 2 ”. 
     Between the two casting lines, the turntable  130  according to the invention can be seen The stationary rotational axis  134  of the turntable  130  lies in the vertical center planes M 1  and M 2  of the first and second reducing stands  116 - 1 ,  116 - 2 ; because of the symmetric arrangement of the individual components of the casting lines, these two planes coincide. In concrete terms, the two center planes M 1  and M 2  coincide because the first and second reducing stands  116 - 1 ,  116 - 2  are on the same level in the casting direction R. it can be seen that the turntable  130  comprises various positions P 1 , P 2 , P 3  for accepting the rolls of the first or second reducing stand  116 - 1 ,  116 - 2 . A pushing and pulling device  160  in the form of, for example, a roll-changing locomotive or a hydraulic cylinder can be arranged in the center of the turntable to move the rolls. It is also possible to see an opening  136  in the center of the turntable; this opening can serve to allow the passage of media lines or power lines for supplying the pushing and pulling device. The boundary between the casting bay  138  and the adjacent bay  140  is also designated in  FIG. 2  by the reference number  139 . It can be seen that, in the case of the exemplary embodiment according to  FIG. 2 , a partial area, more precisely a segment, of the turntable always projects into the adjacent bay  140 . This segment is designated in  FIG. 2  by the reference number  132 . Because this segment projects into the adjacent bay  140 , it is accessible to the crane of the adjacent bay, so that this crane can carry away worn-out rolls from the segment-shaped area of the turntable  130  to, for example, a roll workshop or can set down new rolls from the roll workshop onto the segment area  132  of the turntable. A pushing and pulling device  160  can be seen. on the turntable  130 ; it is supported on rails above the opening  136 . 
       FIG. 2  also shows the intermediate holding station  150 , which, with respect to the casting direction R, is preferably located right at the periphery of the turntable. The intermediate holding station  150  preferably comprises for its own part rail spurs  152  oriented toward the rotational axis  134  of the turntable, on which rail spurs the rolls of the two reducing stands  116 - 1 ,  116 - 2  can be stored on an intermediate basis. The radial orientation of the rail spurs to the center of rotation  134  of the turntable offers the advantage that the rolls can be pushed from the turntable onto the intermediate holding station and vice versa. 
       FIG. 3  shows by way of example a cross section through the casting/rolling installation  100  according to the invention at the level of the common center planes M 1 , M 2  of the first and second four-roll reducing stands  116 - 1 ,  116 - 2 . It can be seen that the two reducing stands  116 - 1 ,  116 - 2  comprise, by way of example, two work rolls  310 , an upper backup roll  320 - 1 , and a lower backup roll  320 - 2 . Between the two reducing stands, the turntable  130  according to the invention can be seen in cross section, on which, by way of example, sets of work rolls  310  have been laid. In the center of the turntable  130  is the previously mentioned pushing and pulling device  160 . 
     A change of rolls, more precisely, the removal of work and backup rolls from, and the installation of such rolls in, the reducing stands  116 - 1 ,  116 - 2  cited by way of example is carried out in the casting/rolling installation according to the invention just described according to the following method: 
     The method for removing at least one of the worn-out work rolls  310  from one of the two reducing stands  116 - 1 ,  116 - 2  of the casting/rolling installation  100  comprises the following steps:
         14a) turning the turntable  130  so that a free second position P 2  on the turntable for receiving the worn-out work roll is positioned opposite the first or second reducing stand  116 - 1 ,  116 - 2 ;   14b) pulling the at least one worn-out work roll  310  by means of the pushing and pulling device  160  out of the first or second reducing stand and onto the turntable  130  in the second position P 2 ;   14c) turning the turntable so that the second position P 2 , which is holding the at least one worn-out work roll  310 , is opposite the intermediate holding station  150 ;   14d) pulling or pushing the at least one worn-out work roll  310  from the turntable  130  onto the intermediate holding station  150 ; and   14e) transporting the worn-out work roll  310  away from the intermediate holding station  150  by means of the crane  142  of the adjacent bay  140  to a roll workshop;       

     or alternatively to steps 14(d) and 14(e), when a partial area of the turntable  130  is accessible to the casting bay crane or the crane of the adjacent bay:
         14d′) transporting the worn-out work roll  310  away from the turntable by means of the casting bay crane or the crane of the adjacent bay.       

     At least one new work roll  310  is installed in the reducing stand  116 - 1 ,  116 - 2  of the casting/rolling installation by means of the following steps:
         15a) performing at least steps 14(a) and 14(b), optionally also steps 14(c) and 14(d);   15b) setting the at least one new work roll  310  by means of the crane of the adjacent bay  140  onto the intermediate holding station  150 ;   15c1) turning the turntable  130  so that a first position P 1  for receiving the at least one new work roll  310  is opposite the intermediate holding station  150 ; and   15c2) pulling or pushing the at least one new work roll  310  by means of the pushing and pulling device  160  from the intermediate holding station until it lies completely in the first position P 1  on the turntable;   15d) turning the turntable so that the first position, which is occupied by the at least one new work roll  310 , is opposite the first or second reducing stand  116 - 1 ,  116 - 2 , from which the at least one worn-out work roll had been previously removed;   15e) pushing the at least one new work roll  310  by means of the pushing and pulling device  160  into the reducing stand  116 - 1 ,  116 - 2 ;       

     or alternatively to steps 15b)-15c2), when a partial area of the turntable is accessible to the casting bay crane or to the crane of the adjacent bay:
         15b′) turning the turntable  130  so that a first position P 1  on the turntable for receiving the at least one new work roll  310  is accessible to the crane  142  of the adjacent bay;   15c′) setting the at least one new work roll  310  by means of the casting bay crane or the crane  142  of the adjacent bay  140  onto the first position on the turntable.       

     The method for removing additional worn-out rolls such as backup rolls  320 - 1 ,  320 - 2  from a reducing stand  116 - 1 ,  116 - 2  of the casting/rolling installation comprises the following steps:
         16a) positioning a roll-change stand on the turntable  130 ;   16b) turning the turntable so that a free third position P 3  on the turntable for receiving the worn-out backup rolls is opposite the first or second reducing stand  116 - 1 ,  116 - 2 ;   16c) pulling out the lower backup roll  320 - 1  from the reducing stand and into the third position P 3  on the turntable  130 ;   16d) setting the backup roll-changing stand onto the worn-out lower backup roll  320 - 1  in the third position P 3 ;   16e) moving the worn-out lower backup roll  320 - 1  together with the backup roll-changing stand set on top into the reducing stand  116 - 1 ,  116 - 2 ;   16f) in the reducing stand: setting the worn-out upper backup roll  320 - 2  onto the backup roll-changing stand;   16g) pulling out the upper and lower backup rolls by means of the backup roll-changing stand from the reducing stand and into the third position P 3  on the turntable  130 ;   16h) turning the turntable  130  so that the third position is opposite the intermediate roll holding station  150 ;   16i) pushing or pulling the backup roll-changing stand with the two backup rolls from the turntable onto the intermediate holding station  150 ; and   16j) carrying away the upper backup roll  320 - 2 , the backup roll-changing stand, and the lower backup roll  320 - 1  in succession by means of the crane  142  of the adjacent bay from the intermediate holding station;
 
or alternatively to steps 16h)-16i), when a partial area of the turntable  130  is accessible to the casting bay crane or to the crane of the adjacent bay:
   16j′) carrying away the upper backup roll  320 - 2 , the backup roll-changing stand, and the lower backup roll  320 - 1  in succession by means of the casting bay crane or the crane of the adjacent bay to the roll workshop.       

     Step 16c) and the following steps are not carried out until after the two work rolls  310  have been removed from the reducing stand  116 - 1 ,  116 - 2 . 
     If, during the course of step 15a), the backup roll-changing stand has already been moved into the third position P 3  on the turntable  130 , it is raised prior to the performance of step 16c) and, after the completion of step 16c), lowered during the course of step 16d) onto the worn-out lower backup roll. 
     The method for installing new backup rolls  320  into a reducing stand  116 - 1 ,  116 - 2  of the casting/rolling installation  100  is carried out by means of the following steps:
         19a) transporting a new lower backup roll  320 - 1  to the intermediate holding station  150  by means of the crane  142  of the adjacent bay;   19b) setting the backup roll-changing stand onto the new lower backup roll  320 - 1  on the intermediate holding station  150  by means of the crane  142  of the adjacent bay;   19c) placing a new upper backup roll  320 - 2  onto the backup roll-changing stand by means of the crane  142  of the adjacent bay;   19d) pulling or pushing the backup roll-changing stand together with the lower and upper backup rolls from the intermediate holding station to the third position P 3  on the turntable  130 ;   19e) turning the turntable so that the third position P 3  is opposite the first or second reducing stand  116 - 1 ,  116 - 2 ;       

     19f) pushing the backup roll-changing stand together with the lower and upper backup rolls  320 - 1 ,  320 - 2  into the reducing stand  116 - 1 ,  116 - 2 ;
         19g) lifting the upper new backup roll from the roll-changing stand and suspending the upper backup roll in the reducing stand;   19h) pulling the lower backup roll  320 - 1  together with the backup roll-changing stand resting on top out of the reducing stand  116 - 1 ,  116 - 2 ;   19i) lifting the backup roll-changing stand from the lower backup roll and depositing it on the turntable  130 ;   19j) pushing the new lower backup roll into the reducing stand and installing it there;       

     or alternatively to steps 19a)-19d), when a partial area of the turntable is accessible to the casting bay crane or to the crane of the adjacent bay:
         19a′) transporting a new lower backup roll  320 - 1  onto the turntable by means of the casting bay crane or the crane of the adjacent bay;   19b′) setting a backup roll-changing stand onto the new lower backup roll on the turntable by means of the casting bay crane or the crane of the adjacent bay; and   19c′) setting a new upper backup roll  320 - 2  onto the backup roll-changing stand by means of the casting bay crane or the crane of the adjacent bay.       

     When any of the methods described above is carried out, the sequence of the individual method steps can, in principle, be varied in any way desired; it is necessary only that the sequence make technical sense. All of the pulling or pushing movements of the work rolls or backup rolls can be carried out by means of the pulling and pushing device. 
     LIST OF REFERENCE SYMBOLS 
     
         
           100  casting/rolling installation 
           110 - 1  first casting line 
           110 - 2  second castling line 
           112 - 1  first mold 
           112 - 2  second mold 
           114 - 1  first roller apron 
           114 - 2  second roller apron 
           116 - 1  first reducing stand 
           116 - 2  second reducing stand 
           118 - 1  first casting platform 
           118  common casting platform 
           120  distributor device 
           126  foundation 
           127  turntable drive 
           128  locking or indexing device 
           129  turntable bearing 
           130  roll-changing device, turntable 
           132  partial area, e.g. a segment 
           134  rotational axis 
           136  opening 
           138  casting bay 
           140  adjacent bay 
           142  crane of the adjacent bay 
           145  cold strand removal device 
           150  intermediate holding station 
           152  rail spur on the intermediate holding station 
           160  pulling and pushing device 
           180  tundish 
           190  casting hall crane 
           192 - 1  first shears 
           192 - 2  second shears 
           193  scrap box 
           194  tunnel furnace 
           194 - 1  first tunnel furnace 
           194 - 2  second tunnel furnace 
           195  finishing mill 
           196  cooling section 
           197  reel device 
           198  control stand 
           210 - 1  first cast strand 
           210 - 2  second cast strand 
           220 - 1  slabs of the first casting line 
           220 - 2  slabs of the second casting line 
           230 - 1  hot-rolled strip of the first casting line 
           300  intermediate space 
           310  work roll 
           320 - 1  upper backup roll 
           320 - 2  lower backup roll 
         BS 1 , BS 2  operating sides 
         d distance 
         R casting direction 
         r radius 
         M 1 , M 2  center planes 
         P 1 , P 2 , P 3  positions