Abstract:
The invention relates to a casting roller ( 1 ), for a double-roller continuous casting machine, in particular for the casting of a steel strip, comprising a cylinder sleeve ( 2 ) which may rotate about a fixed axle ( 5 ). Intermediate rings ( 7   b,    7   c,    7   d ) rotating with the cylinder sleeve ( 2 ) are arranged between the cylinder sleeve ( 2 ) and the axle ( 5 ), which are provided with radial pressure means ( 9 ), acting on the cylinder sleeve ( 2 ). The above comprise a pressure chamber ( 10 ), pressurized with a fluid pressure medium and acting on a pressure ring ( 24 ) fixed to the inner wall of the cylinder sleeve ( 2 ), which may be deformed in the radial direction by inductive heating or radiated heat. The external profile of the casting roller ( 1 ) may be globally altered or local fine adjustments made by pressurizing the pressure chamber ( 10 ) with the pressure medium, or by heating the pressure ring ( 24 ).

Description:
BACKGROUND OF THE INVENTION 
     The invention concerns a casting roll for a twin-roll casting machine, especially for casting steel strip, with a cylinder sleeve, which rotates on a stationary axle. 
     Casting machines of this type work in such a way that, during the operation, the molten metal present in the mold space flows through the casting gap between the counterrotating casting rolls and is shaped into a metal strip. 
     Due to the high thermal load, the casting sleeves experience convex deformation, which results in a concave profile of the cast strip. This can result in diminished strip quality, especially since the cooling of the strip also causes transverse shrinkage of the strip. For this reason, the casting rolls are concavely shaped in the cold state, so that thermal expansion of the casting rolls produces a parallel or slightly convex shape of the strip, which allows noncritical transverse contraction during cooling of the strip and guarantees the accuracy to gage of the strip. 
     However, a disadvantage of casting rolls of this type is that, due to their concave shape, they can be used only for a certain influx of molten metal and thus heat input into the casting rolls. If the production parameters and thus the amount of molten metal flowing into the mold are changed, a different heat input and thus different thermal deformation of the casting rolls are obtained, which can result in the cast strip no longer being accurate to gage. The result of all this is that the casting rolls need to have different geometries for different production parameters. 
     Another disadvantage of concave casting rolls arises during the starting up of the casting machines without a dummy bar. Since in this case the casting gap cannot be completely closed when the casting rolls are run together, liquid steel then leaks out at the bottom, which makes a controlled start-up more difficult. 
     SUMMARY OF THE INVENTION 
     The objective of the invention is to avoid these disadvantages and to create a casting roll of the type described above, whose outer contour can be adjusted globally or locally by means that are simple in design and that can be easily and sensitively controlled. 
     In accordance with the invention, this objective is achieved by installing one or more intermediate rings and/or supporting rings between the cylinder sleeve and the axle. These rings are provided with pressure means that act on the cylinder sleeve. The pressure means are preferably nonrotatably connected with the cylinder sleeve and have a pressure chamber bordering on the inside wall of the cylinder sleeve. A fluid pressure medium can be admitted into the pressure chamber through supply channels in the axle and in the intermediate ring. 
     When the fluid pressure medium is admitted into the pressure chamber, uniform radial pressure is exerted on the cylinder sleeve. This causes expansion of the cylinder sleeve. Suitable positioning of the intermediate ring or rings along the axle and suitable admission of pressure medium into the pressure chambers make it possible at all times to achieve sensitive adjustment of the profile of the casting sleeve and thus the profile of the strip during the casting process. Accordingly, this makes it possible to compensate for changes in the process parameters without production interruptions. Starting up with or without a dummy bar is also considerably simplified, since it is now possible to bring the conventionally concave form of the casting roll into a cylindrical form, which guarantees complete closing of the casting gap when the casting rolls are run together. This allows a controlled start-up, because molten steel cannot flow out towards the bottom. 
     To ensure that pressure acts uniformly on the cylinder sleeve, the invention provides that the pressure chamber is annular and completely encircles the intermediate ring. 
     It is advantageous for the end face of the intermediate ring to abut the inside wall of the cylinder sleeve and for the intermediate ring to have a cavity that forms the pressure chamber. The cavity is bounded at its end face by a flexible seal, which is installed in the cavity and rests against the inside wall of the cylinder sleeve. 
     In another design in accordance with the invention, a circumferential intermediate gap is present between the intermediate ring and the inside wall of the cylinder sleeve and is spanned by a metal seal that bounds the pressure chamber. 
     In another variant of the invention, the intermediate ring abuts the inside wall of the cylinder sleeve and has a cavity that forms the pressure chamber, which is bounded on its end face by the inside wall of the cylinder sleeve and is surrounded by one or more outer seals installed in the cylinder sleeve. 
     It is advantageous for the intermediate ring to be rotatably positioned on the stationary axle and to be provided with one or more seals that seal the transition between the supply channels in the axle and in the intermediate ring. 
     In an alternative variant of the pressure means of the invention, the invention provides that the pressure means have a co-rotating pressure ring, which is fixed on the inside wall of the cylinder sleeve, rests circumferentially on the intermediate ring and can be expanded in the radial direction by inductive heating. When the pressure ring is heated, it is more or less expanded, and consequently the cylinder sleeve is expanded. In this way, here too it is always possible to adjust the casting roll profile and thus the strip profile as well during the casting process. 
     It is advantageous for the pressure ring to be provided with thermal insulation. 
     In the case of casting rolls with several intermediate rings, it is advantageous if they can be moved along the stationary axle. 
     It is also advantageous if the contact surfaces between the intermediate rings and the inside wall of the cylinder sleeve lie on a common surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The invention is explained in greater detail below with reference to several embodiments illustrated in the drawings. 
         FIG. 1  shows a casting roll of the invention with several intermediate rings, whose pressure means are pressurized with a fluid pressure medium. 
         FIG. 2  shows the casting roll from  FIG. 1 , whose intermediate rings are provided with variants of the pressure means shown in  FIG. 1 . 
         FIG. 3  shows a variant of the casting roll shown in  FIGS. 1 and 2 , whose intermediate rings are installed outside a central centering and water admission. 
         FIGS. 4 to 6  show enlarged views of the pressure means of the casting rolls of  FIGS. 1 and 2 . 
         FIG. 7  shows the pressure means of the casting roll of  FIG. 3 , also shown as an enlargement. 
         FIG. 8  shows a partial section at one of the bearings of the cylinder sleeve, in which pressure means are also present. 
         FIG. 9  shows a casting roll in cross section with a variant of the pressure means. 
         FIG. 10  shows a partial section through the pressure means of  FIG. 9 . 
         FIG. 11  shows a top view of a portion of segments of the pressure means. 
         FIG. 12  shows a casting roll in cross section with another variant of the pressure means. 
         FIG. 13  shows a partial section through the pressure means of  FIG. 12 . 
         FIG. 14  shows an enlarged view of the fastening device in arrow direction XIV in  FIG. 13 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The casting roll  1  in  FIG. 1  has a cylinder sleeve  2  with supporting rings at its end faces, which, together with the cylinder sleeve  2 , can be rotated on a stationary axle  5  supported on bearings  6 . Three intermediate rings  7   a  are installed inside the casting roll  1  and serve the purpose of adjusting the outer profile of the casting roll  1 . The intermediate rings  7   a  re positioned on the stationary axle  5  with spacers  8 , which are mounted on the supporting rings  3  and  4 . 
     The intermediate rings  7   a  rotate together with the cylinder sleeve  2 . This co-rotation is effected by the spacers  8  and the supporting rings  3  and  4 . 
     As  FIG. 4  shows, the intermediate rings are provided with pressure means  9  with a pressure chamber  10 , which has an annular design and encircles the intermediate ring  7   a  around its entire circumference. A fluid pressure medium, such as hydraulic oil or the like, can be admitted into the pressure chamber  10  through supply channels  11 ,  12  in the axle  5  and in the intermediate ring  7   a.  High-viscosity pressure media can be used to apply the necessary pressures. The transition between the supply channels  11  and  12  is sealed with sealing elements  13  installed in the intermediate ring  7   a.  The end faces of the intermediate rings  7   a  abut the inside wall  14  of an annular projection  15  of the cylinder sleeve  2 , and the intermediate rings  7   a  have an annular groove  16 , which forms the pressure chamber  10  and is bounded at its end face by a flexible seal  17  inserted in the annular groove  16 . The intermediate rings  7   a  also have a shoulder  18 , which interacts with the spacers  8  and serves as a positioning aid. 
     The casting roll in  FIG. 2  differs from the casting roll in  FIG. 1  essentially by the fact that its intermediate rings  7   b,    7   c,  and  7   d  have designs that are different from that of the intermediate rings  7   a.    
     In  FIG. 5 , which shows the intermediate ring  7   b,  a circumferential intermediate gap  19  is present between the intermediate ring  7   b  and the inside wall  14  of the cylinder sleeve  2  and is spanned by a metal seal  20  that bounds the pressure chamber  10 . The metal seal  20  is inserted in annular grooves  21   a,    21   b  in the intermediate ring  7   b  and the cylinder sleeve  2 , respectively. It is secured there by an annular flange  22 , which is mounted on the side of the intermediate ring  7   b.  The intermediate ring  7   b  is also positioned relative to the cylinder sleeve  2  by the metal seal  20 , so that the shoulder  18  that would otherwise be present, as in the case of the intermediate ring  7   a,  can be eliminated. 
     The intermediate ring  7   c  shown in  FIG. 6  differs from the intermediate ring  7   a  only in that the flexible seal  17  is not present, and that the end face of the pressure chamber  10  is bounded by the inside wall  14  of the cylinder sleeve  2  and is surrounded by seals  23  installed in the cylinder sleeve  2 . In intermediate rings  7   a  and  7   c,  the annular groove  16  is designed with a rectangular cross section. However, it is immediately possible in accordance with the invention to design the annular groove  16  with a semicircular cross section. It is also immediately possible to provide several partial annular grooves distributed along the circumference instead of a fully circumferential annular groove. 
     The intermediate ring  7   d  in  FIG. 7  differs from the intermediate rings  7   a,    7   b,  and  7   c  in that it is mounted in a stationary way on the stationary axle and does not rotate with the cylinder sleeve. A pressure ring  24 , which is mounted in a stationary way and rotates with the cylinder sleeve, is provided on the inside wall  14  of the cylinder sleeve  2  and can be expanded in the radial direction by inductive heating. The pressure ring  24  replaces the pressure chamber  10  of the intermediate rings  7   a,    7   b,  and  7   c,  which can be pressurized by a pressure medium. The cylinder sleeve  2  is expanded by this pressure ring  24 . To further intensify this effect, the pressure ring  24  is provided with insulation  25 , which thermally insulates it from the cylinder sleeve  2  and the intermediate ring  7   d.  The pressure ring  24  can be heated not only inductively from the stationary axle  5 , but also by radiant heat, but in this case, no insulation is provided between the pressure ring and the intermediate ring. 
     The casting roll in  FIG. 3  differs from the casting rolls in  FIGS. 1 and 2  in that its intermediate rings  7   a ′ are not seated directly on the stationary axle  5 , but rather are supported on a coaxial support cylinder  26 , which is nonrotatably joined in the middle with the cylinder sleeve  2  by means of clamping rings  27  and can rotate on the stationary axle  5  together with the cylinder sleeve  2  and the intermediate rings  7   a ′. Bearings  28  for the support cylinder  26  are provided on the axle  5 . To position the intermediate rings  7   a ′, the inside wall  14  of the cylinder sleeve  2  is provided with projections  29 , and the intermediate rings  7   a ′ are installed by being stopped against the projections  29 . As a result, the intermediate rings  7   a ′ have different diameters, starting from the center. The central arrangement of the support cylinder  26  relative to the cylinder sleeve results in the further advantage that, with a possible wedge shape of the strip to be produced, equalization can be ensured by decreasing or increasing the casting gap on one side, as necessary. 
     By contrast, in the casting roll in  FIG. 1 , the intermediate rings  7   a  have the same diameter, so that their contact surfaces with the inside wall  14  of the cylinder sleeve  2  lie on a common surface. 
     The casting rolls of the invention in accordance with  FIGS. 1 ,  2 , and  3  offer individual, multiple operational and positioning possibilities for the intermediate rings  7   a,    7   a ′,  7   b,    7   c,  and  7   d  for the profile adjustment of the cylinder sleeve  2  in the axial direction of the casting roll. 
     The intermediate rings  7   a,    7   a ′,  7   b,    7   c,  and  7   d  produce negligible supporting forces on the stationary axle of the casting roll. The relative motion between the rotating cylinder sleeve  2  and the stationary axle  5  occurs with extremely low sealing frictional forces. 
     In addition, the casting roll of the invention is characterized by the fact that it guarantees simple assembly and disassembly, especially of the cylinder sleeve  2 . 
     It is also distinguished by a small structural space in regard to other elements that are to be installed inside the cylinder sleeve  2 , such as vibrators, magnetic elements, or the like. 
     In regard to the casting roll of the invention, the invention also takes into account the fact that, due to the different dimensional stability of the cylinder element  2  and the intermediate rings  7   a,    7   a ′,  7   b,    7   c,  and  7   d,  the latter experience less deformation than the cylinder sleeve  2 . This can be influenced by a suitable choice of materials for these parts. 
     In regard to the expansion of the cylinder sleeve  2  by means of the intermediate rings  7   a,    7   a ′,  7   b,    7   c,  and  7   d,  naturally, the thermal expansion of the cylinder sleeve  2  is also taken into consideration. 
       FIG. 8  shows another enlarged sectional view of the terminal bearing of the cylinder sleeve  2  of a supporting ring  4 , which is also designed as an intermediate ring in accordance with the invention. For this purpose, in a given supporting ring  4 , pressure means  9 ′ that act on the cylinder sleeve  2  are provided. It is advantageous for these pressure means  9 ′ to be installed at an angle towards the cylinder sleeve, for example, an angle of about 30°            from the horizontal, so that it does not act on the sleeve  2  radially, but rather at the corresponding angle. The pressure means  9 ′ have a pressure chamber  10 , which again are connected to a source of pressure medium by supply channels  11 .
     The surface of the cylinder sleeve can be caused to vibrate by pulsation of the pressure medium in at least one intermediate ring or by a vibrator installed on at least one intermediate ring, so that heat dissipation can be influenced or increased. 
       FIGS. 9 and 10  show a variant of the pressure means  59  by which the cylinder sleeve  2  can be expanded. Preferably, in analogy to the embodiment shown in  FIG. 1 , several pressure means  59  of this type are installed along the cylinder sleeve  2 , which make it possible for this sleeve  2  to be uniformly expanded at least over a portion of its total length. 
     The pressure means  59  have an expansion ring  51 , between the axle and which a pressure chamber  55  is formed, which is connected to a pressure medium supply  54  and is laterally sealed by suitable sealing means  52 ,  53 . The expansion ring  51  is surrounded by a spiral bush  56 , which has a spiral design and an axis coaxial to the axis of the axle  5  and which, during an expansion, expands accordingly. This spiral bush  56  forms the inner ring of an encapsulated roller bearing  57 , which on the outer side is likewise formed by a spiral bush  56 ′ of this type. Segments  58 ′ that form a ring are also present between the spiral bush  56 ′ and the cylinder sleeve  2 . The outer surfaces of these segments  58  abut the inside of the sleeve  2 . 
     The expansion ring  51  radially expanded by the pressure medium, for example, a hydraulic oil, expands the inner spiral bush  56 , which in turn expands the outer spiral bush  56 ′ via the rollers, and the outer spiral bush  56 ′ then expands the cylinder sleeve  2  via the ring  58 . These pressure means  59  result in the advantage that, with the expansion ring  51  acted on by a pressure medium and with the spiral bush  56  surrounding the expansion ring  51 , no rotating parts are present, so that a seal with greater operational reliability is possible. 
       FIG. 11  shows a top view of part of the ring that consists of segments  58 . These segments  58  mesh together by corresponding peaks and congruent recesses. 
     Another variant is shown in  FIGS. 12 ,  13 , and  14 , which illustrate pressure means  69  designed similarly to the pressure means of  FIGS. 9 and 10 . In this case, an expansion ring  71  that surrounds the axle  5 , a roller bearing  57  with spiral bushes  76 ,  76 ′ as the inner and outer rings, and a ring  78  are also provided. 
     As shown in  FIG. 14 , the ring  78  is divided by a slot  81 . This ring  78  and with it the inner spiral bushes can be more or less compressed for assembly by means of a fastening device  80  and thus changed in diameter. For this purpose, the fastening device consists of pins  82 ,  83 , which are fastened to the ring  78  on both sides of the slot and are surrounded by a flexible ring element  84 . One of the pins  83  has a cam  83 ′. The ring  78  can be compressed or loosened by turning this cam  83 ′. 
     For different roll diameters of the casting machine, one or more such rings  78  with at least one slot  82  may be provided between the outer spiral bush  76 ′ and the inner side of the cylinder sleeve  5 .