Patent Publication Number: US-2012042706-A1

Title: Reversing roll stand having inlet and outlet guides

Description:
The invention relates to a reversing roll stand, in particular a Steckel reversing roll stand, with at least one upper backing roll and one lower backing roll and respective upper and lower working rolls with respective upper and lower guides on the input side of the stand and the output side of the stand. 
     In the rolling of slab ingots in roughing stands, in reversing operation slab ingots with a thickness of about 250 mm are rolled out to form rough strip with a thickness of about 40 mm. Reversing roll stands of this type have vertically guided upper input and output guides mounted in the stand. During the rolling operation, these upper input guides on the input side of the stand and the upper output guides on the output side of the stand rest on bars fixed between the upper working roll chocks of the reversing roll stand. To change a roll, the upper input and output guides are vertically displaced and release the upper working roll chocks. The support bars are installed in the roll workshop according to the current working roll diameter with a defined distance from the roll surface. Support bars are also installed in the lower working roll chocks. However, they are not in contact with lower guides, there being no contact between support bars and working rolls at the top as well as at the bottom in a reversing roll stand of this type. This is not necessary either, since due to the very large minimum rough strip thickness of about 40 mm, there is no danger that rolling material will reach into the nip between working rolls and support bars. 
     In finishing stands, the rough strip thicknesses of then about 40 mm are rolled out to a final strip thickness of up to about 1 mm. This is carried out either in a multiple-stand finishing mill in tandem arrangement or in one or two stands in a Steckel arrangement. In Steckel reversing roll stands, the rough strip in reversing operation is rolled out in several roll passes to form the finished product with a final strip thickness of up to about 1 mm. In finishing stands of this type, the upper scrapers usually arranged on the upper input and output guides as well as lower scrapers likewise assigned to the working rolls, which likewise are provided on the input side of the stand as well as on the output side of the stand, are in constant contact with the respectively upper or lower working roll. This is necessary in order to shield the strip surface from roll cooling water or also in order to scrape off any rolling material possibly adhering to the working rolls therefrom. With a change of working roll, these upper and lower scrapers must be pulled back far enough from the respectively assigned working roll that a working roll change is possible. 
     Based on the different mode of operation and embodiment of roughing stands and finishing stands described above, different stand types or differently equipped stand types are to be used depending on the purpose, which entails a correspondingly complex stockpiling for a factory. There is therefore a need to achieve a simplification here. 
     The object of the invention is to create a solution that makes it possible to use a reversing roll stand as a roughing stand as well as a finishing stand. 
     This object is attained according to the invention by a reversing roll stand with the features of claim  1 . Advantageous further developments and expedient embodiments of the invention are the subject matter of the dependent subordinate claims. 
     The invention is a reversing device that meets the requirements for a “roughing stand operation” as well as for a “finishing stand operation.” With the reversing roll stand according to the invention it is possible to press the upper and lower scrapers against the respective working rolls as well as to swing clear the upper and lower guides for a roll change. In particular, Steckel reversing roll stands can be equipped therewith such that when roughing and when finishing they can roll out slab ingots with a thickness of about 250 mm in reversing operation to form a finished product with a final strip thickness of about 1 mm. 
     According to a first embodiment, the upper support is connected by an actuator and a coupling to the upper backing roll support beam and thus is displaceable relative to the lower vertical guide and can be drawn out of it. The upper supports can thus be moved out of the working space of the working rolls by a simple mechanism and thus release the upper working roll chocks. 
     Preferably, clamping heads, ball heads and universal joints or simply moveable threaded connections are hereby used as couplings. 
     Another embodiment of the invention provides that a third actuator that can move the upper support connects this support to the stand or is attached to the backing roll support beam. Thus, depending on the available installation space, an optimal attachment of the upper supports is selected, which in particular in the course of possible maintenance or repair work is easily accessible and easy to assemble or disassemble. 
     Another embodiment of the invention provides that an upper scraper juxtaposed with the upper working roll, and this scraper can be adjusted or pressed against the working roll by a second actuator. The second actuator ensures that the scraper always has uniform contact with the upper working roll over its entire length. Wear of the scraper edge is then preferably compensated by continuously pressing the scraper against the working roll by the second actuator. 
     Another embodiment of the invention provides that a lower scraper with a fourth actuator is arranged such that the scraper is pressed against the working roll or is moved away from the working roll by the actuator and thus can be swung clear of the installation area or removal area of the working rolls. Thus the installation space for the working rolls is freely accessible, without major installation work on the arranged scrapers being necessary. Both scrapers now lie outside the outer extents of the working roll chocks and are clear of them during a working roll change. 
     The arrangement of the scrapers can be provided in a special embodiment of the invention such that swinging clear the scrapers can be carried out upward and/or downward. A flexible adjustment to the existing space conditions is thus possible. 
     The embodiment of the invention described above is further benefitted in that the upper and lower scraper is cardanically mounted. With this type of mounting, swinging clear in any direction is rendered possible 
     Thus in a further embodiment of the invention it is shown that the upper and lower scraper can be pivoted out from the working space between the working roll chocks. 
     In a further embodiment of the invention the actuators are lift cylinders in the form of a hydraulic cylinder or pneumatic cylinder or in the form of a driven spindle. It is therefore possible according to the connections present where installed, such as, for example, hydraulic connections, pneumatic connections or electric connections or a combination of all three according to the structural conditions, to select an optimal actuator that takes up as little of the installation space of the working rolls as possible and provides an optimal adjustment mechanism. 
     In a further embodiment of the invention the upper support on the reversing roll stand is pivoted on connecting elements on which one end of a lift cylinder with clamping head and one end of a second pneumatic cylinder acts. Depending on the construction of the connections of the connecting element, for example, the arrangement of different bores, a corresponding angular adjustment of the lift cylinders with respect to one another is possible and thus can be adjusted to the space conditions. 
    
    
     
       The invention is described in more detail below by way of example based on the drawing. Therein: 
         FIG. 1  is a schematic section through part of a Steckel reversing roll stand, the left side showing the position during rolling and the right side the position during exchange of working rolls, 
         FIG. 2  is a diagrammatic view in the rolling direction of part of a Steckel reversing roll stand, and 
         FIG. 3  are diagrammatic top views showing on the left part of an upper support and on the right part of a lower guide in their operational position when rolling. 
     
    
    
     As shown on the left of  FIG. 1 , when rolling, an upper working roll  1  and an upper backing roll  2  as well as a lower working roll  3  and a lower backing roll  4  are in contact with one another. In the roll position shown only on the left, upper scrapers  11  engage the upper working roll  1  and lower  13  engage the lower working roll  3 . The upper scrapers  11  are mounted on respective upper supports  8  connected by respective actuators  6 , for example, a lift cylinder with clamping head, to an upper-backing roll support beam  5 . Each upper support  8  is guided in respective lower vertical guides  9  and respective upper vertical guides  10  in the Steckel reversing roll stand shown at  20 . The upper scrapers  11  are pivotal on the upper support  8 , in particular by means of universal joints. Second actuators  12 , for example pneumatic cylinders carried on the upper supports  8 , can pivot the upper scrapers  11  against the respective upper working roll  1 . A rotation axis  16  about which the upper scraper  11  can be rotated is positioned such that the edge of the upper scraper  11  can be brought into contact with the upper working roll  1  over the entire length of the scraper  11 . Wear occurring on the longitudinal edges of the upper scrapers  11  is compensated for by continuous adjustment action of the respective second actuators  12 . The first actuator  6  with clamping head, which is pivotal on the upper backing roll support beam  5 , is pivoted on the upper end of the upper support  8  and when rolling as shown on the left in  FIG. 1  is locked such that it rigidly connects the beam  5  and the upper support  8 . All necessary or resulting changes in the height of the roll nip  15  are followed when rolling by the locked upper supports  8  via the upper backing roll support beam  5 . The strokes of the first actuators  6  are adjusted according to the current working-roll diameters and backing roll diameters in a position-regulated manner and locked by means of the clamping head integrated into the lift cylinder  6 . 
     The lower scrapers  13  are also pivotal, preferably cardanically, about axes or rotation points  17  in the area of the lower working roll  3  on the reversing roll stand  20 . With the aid of fourth actuators  14  (not shown in detail), the lower scrapers  13 , preferably located ahead of a support beam, are pressed against the lower working roll  3  in a manner analogous to the upper scrapers  11 . 
     As can be seen in particular from  FIGS. 2 and 3 , two fourth actuators  14  are assigned to each lower scraper  13 , positioned symmetrically to the lower scraper  13  and on the one hand are supported on the lower scraper  13  and on the other hand are supported on the reversing roll stand  20  or elements arranged thereon. Likewise, two symmetrically arranged lift cylinders  6  are assigned to each upper support  8  and one lower vertical guide  9  and one upper vertical guide  10 , which interact with corresponding counter-elements carried on the reversing roll stand  20 , are provided at each end of each upper support  8 . 
     Each upper support  8  is pivotable about an axis  21  on a connecting element  19  attached to the lift cylinder  6  and a third actuator  7  has one end also pivoted at an axis  22  on the connecting element  19  and another end pivotable about an axis  23  to part of the respective upper support  8  at a location spaced from the connecting part  19 . A plurality of the third actuators  7  is thus assigned to each upper support  8  like the number of first actuators  6 . In the illustrated embodiment there are two hydraulic cylinders. 
     In order to now move the lower scrapers  13  and the upper scrapers  11  into the roll-change setting or position shown on the right in  FIG. 1 , which position makes it possible to change the upper and lower working rolls  1  and  3 , the upper supports  8  on the input and on the output side of the stand are raised by the respective upper backing roll support beam  5  together with the upper backing roll  2  so far that the upper working roll  1  and the upper backing roll  2  move out of contact with one another, as shown on the right in  FIG. 1 . Subsequently, the clamping heads of the lift cylinder  6  are released and the upper supports  8  are lifted by the first actuators  6  so far that these upper supports  8  leave the lower vertical guides  9  and can be pivoted about the axes  24  while still guided in the upper vertical guides  10 . This pivoting movement is now effected by the third actuators  7 , which to this end retract their piston rods into their pistons and shorten, so that the upper supports  8 , as shown in the right in  FIG. 1 , pivot outward and thus release the region of the upper working roll  1  for a change of the upper working roll  1 . Subsequently, the lower scrapers  13  are pivoted by the fourth actuators  14  into the open position shown in the right in  FIG. 1 . The upper scrapers  11  as well as the lower scrapers  13  pivot outward away from the working rolls  1  and  2 . After the lower scrapers  13  have reached their roll-change position, the lower backing roll  4  is lowered so far that the lower working roll  3  rests pm working roll extension rails  18  in the reversing roll stand  20 . With further lowering of the lower backing roll  4 , the lower working roll  3  and the lower backing roll  4  then also go out of contact with each other so that the lower working roll  3  can now also be replaced. 
     In roll-change position shown on the right in  FIG. 1 , the upper scrapers  11  as well as the lower scrapers  13  are so far outside the outer extents of the working roll parts or working roll chocks that they can be removed to change and expose the working roll.