Patent Publication Number: US-6698497-B1

Title: Strip casting machine comprising two casting rollers

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a strip casting machine, comprised of two casting rollers arranged essentially parallel to each other. 
     2. Description of the Related Art 
     It is well-known to produce by means of strip casting machines continuous strips of liquid melted metal, especially of melted steel. In this connection, the liquid metal is continuously fed to a casting gap defined by driven casting rollers. The liquid metal solidifies in front of and within the casting gap, and an at least partially solidified strip is removed by the casting rollers. This strip may be subjected to further continuous or discontinuous treatment like cooling, reheating, hot or cold rolling, profile transforming, surface treatment, trimming or the like. 
     It is also well-known in connection with strip casting machines, having two casting rollers arranged essentially parallel to each other, to delimit the casting gap with narrow lateral guides. Such narrow lateral guides can rest against end faces of the casting rollers or can be inserted between casing surfaces or roll barrels of the casting rollers and be arranged to be displaceable, for example, for adjusting the format of the strip. The casting rollers are arranged in a stand and can be displaced or pivoted essentially transversely relative to the longitudinal axis of the casting rollers in order to adjust the strip thickness. For cooling the liquid metals, the casting rollers, in particular, the roll barrels of the casting rollers, are cooled intensively by a cooling medium from the interior and/or from the exterior. Generally, the casting rollers are composed of different materials, wherein a material of high thermal conductivity is selected for the cooled roll barrels and a high strength steel is selected for bearing journals and roller core. The bearing journals, the roller core, and the roll barrels form a roller unit which can be set into rotation by means of a drive. The drive action is introduced into the bearing journals and transmitted by them onto the roll barrels. This configuration already known from classic rolling mill design or from the classic design of driving rollers for billet or slab continuous casting machines requires space laterally of the casting machine for the drives and thereby impairs the lateral access to the casting gap and to the narrow lateral guides delimiting the casting gap in its length. This known casting roller configuration also affects the configuration of the stand, the space requirement for multi-strand casting machines, the exchange of casting rollers and narrow lateral guides, the protection against oxidation of the liquid metal and of the cast strip, and the activities for operating and maintaining the machine. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention, the strip casting machine is composed of two casting rollers arranged parallel to each other, forming a casting gap delimited on both sides by narrow lateral guides, and a stand supporting the casting rollers, wherein the casting rollers are provided with cooled roll barrels forming the adjustable casting gap. Bearing journals are provided for supporting the casting rollers on the stand, wherein the cooled roll barrel is composed essentially of a cylindrical casing. The casing of each casting roller is supported on at least both sides thereof by support elements which are mounted rotatably on a stationary axle attached to the stand, wherein at least one of the support elements is drivable. 
     This object is solved according to the invention by the sum of the features of claim 1. 
     It is possible with the invention to position the casting roller drive such that the requirements stated in the object can be satisfied. Furthermore, the configuration of the roller can be better adjusted to the requirements of a casting roller in the sense of a cooled casting mold as can be seen from the subsequent description. In addition to the protection against oxidation of the metal feed, a protection against oxidation of the cast product, entailing corresponding quality improvements, is made possible more easily with the strip casting machine according to the invention. 
     The supporting members, on the one hand, can be a part of the casing, and/or, on the other hand, form a part of the stationary axle. All supporting members can also be a part of the cooled casing of the casting roller such that the casing with the supporting members forms a unitary member and is rotatably supported on the stationary axle. The supporting members are advantageously configured as concentric bearing rings connectable to the casing and supported on the stationary axle. 
     For example, the drive can engage the casing part of the casting roller directly or indirectly. An advantageous solution is accomplished when a first portion of the length of the bearing rings projects into the casing and is provided with cooling water inlet and outlet bores for cooling water circulation between the stationary axle and the casing. A second portion of the length of the bearing rings projects out of the casing and is provided at one side, at least, with bearing and drive members for a rotating movement of the casing, fixedly connected with the bearing rings, on the stationary axle. A straining ring with engaging keys is provided between the bearing rings and the casing. 
     The casting roller drive can be configured in many different ways according to the prior art solutions. An advantageous and simple solution results when a crown gear, being in active connection with a toothing of a stationary drive, is connected to the bearing ring. A driving gear, for example, can be flanged to the stationary axle. 
     As an alternative solution, it is suggested that one or several annular torque motors drive the casing by way of the bearing rings. Particularly advantageous is the drive of the casting rollers by means of a motor, preferably a brushless annular torque motor, arranged on or at the axle. 
     Various solutions are feasible for the supply and removal of the cooling medium through the stationary axle and the bearing rings relative to the casing of the casting rollers. For an advantageous configuration alternative, it is suggested to provide the bearing rings preferably with radial bores and grooves for feeding the cooling medium from the stationary axle to the casing. With this configuration, the stationary axle can be provided with axial bores on both sides and with radial bores at the end area of the axial bores which radial bores are aligned with the grooves of the bearing rings. 
     Also, the process of cooling the casing itself can be accomplished according to various prior art solutions for a circulation of the cooling medium. A simple and very cooling-effective solution results when the casing is provided across its circumference with bores for the circulation of a cooling medium, which bores are parallel to the longitudinal axis of the roller, wherein the direction of flow changes from bore to bore. The number of the bores must therefore be even. 
     In order to shorten the time required for changing the casting rollers, the stationary axle is provided with inlet and outlet means for the cooling medium, which simultaneously connect or disconnect inlet or outlet lines for the cooling medium when the rollers are placed onto or are lifted off the stand, and/or water clamping plates for feeding water and/or multi couplings for grease, energy supply, gas supply, for example, inert gas or air, and control are provided. 
     A simple and quick positioning and fixation of the casting rollers is accomplished when the stationary axle is provided on-both sides of the casing with a stop surface and a support face and when the stand is provided with stop and support surfaces for placing the casting rollers from above. For the fixation of the stationary axle, a swivel arm, for example, can be pivotably connected as a fastening means on both sides of the stand, respectively. 
     For calming the melted bath within the casting gap, an electromagnetic brake can be arranged between the rotating casing and the stationary axle. A particular advantage with regard to positioning and attaching such an electromagnetic brake is seen in that it can be arranged stationarily on the stationary axis. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will be further explained in the following with the help of configurational embodiments. It is shown in: 
     FIG. 1 a schematic view of a partially illustrated strip casting machine, and 
     FIG. 2 a vertical section of a casting roller, 
     FIG. 3 an enlarged detail of a casting roller with a cooled casing and a direct drive by means of an annular torque motor. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In FIG. 1, two casting rollers  1  and  2 , arranged essentially parallel to each other, having cylindrical casings  4  are schematically arranged on a stand  3  which is indicated in a dash-dotted line. A casting gap  6 , delimited on both sides of the casting rollers  1  and  2  by narrow lateral guides  5 , is indicated by dimension lines. Such a casting gap  6  can measure between 1-15 mn, preferable 1.5-5 mm. Bearing journals  8 ,  9  of the casting rollers  1 ,  2  are configured at their support surfaces  10 ,  11  to be square-shaped. Stop surfaces  12 ,  13  of the bearing journals  8 ,  9  are utilized as roller stops on the stand  3 . At least one of the stop surfaces  12 ,  13  of the bearing journals  8 ,  9  can be adjusted by means of position-controlled cylinders arranged within the stand  3  and provided for adjusting the desired casting gap. For simplification purposes, a double arrow is shown in FIG. 1 in this regard. Aligning the fixed roller can be accomplished by means of position-controlled cylinders. For this purpose, setting spindles can also be provided or other setting means acting similarly. Toothed wheels for driving the casting rollers  1 ,  2  are schematically shown with reference numerals  15 ,  15 ′. Such strip casting machines can be used for various casting metals, preferably for producing steel band. 
     FIG. 2 illustrates with reference numeral  21  a casting roller on an enlarged scale compared to FIG.  1 . The casting roller  21  is supported on a stand  23  which is only shown partially. A stationary axle  24  penetrating the entire roller  21  is supported with its square ends on the stand  23  across an approximate length  25 . The length of a roll barrel of a casting roller  21  is indicated by an arrow head  26 . This roll barrel is essentially comprised of a cylindrical casing  27  fixedly connected to two bearing rings  29 ,  29 ′ by means of engaging keys  28  having a straining ring. The casing  27  is cooled by a cooling medium, preferably water. The two bearing rings  29 ,  29 ′ are supported on the axle  24  by sliding bearings, ball bearings, or roller bearings  31 . A first portion of the length of the bearing rings  29 ,  29 ′ protrudes into the casing  27  and is provided with radial inlet and outlet bores  32  for cooling water, which bores open into grooves  33 . The grooves  33  are aligned with radial inlet and outlet bores  34 ,  42  of the stationary axle  24  and of the casing  27 . The cooling water is fed from the stand  23  into the bearing rings  29 ,  29 ′ and into the casing  27  by way of further bore holes  30 ,  30 ′ within the axle  24 . 
     A second portion of the length of the bearing rings  29 ,  29 ′ projects out of the casing  27  and the bearing ring  29  is in active connection with a drive, for example, a gear wheel drive  36 , for the casting roller  21 . The gear wheel drive  36 , if desired, can be flanged to the stationary axle  24 . It engages a crown gear  37  screwed down on the bearing ring  29 . Instead of the illustrated gear wheel drive  36 ,  37 , it is possible, as an alternative solution, to drive the casting roller  21  with one or several annular torque motors. 
     Cooling the roll barrels of the casting rollers or the cylindrical casings  27  across its circumference can be ensured by a circulation of cooling water through axially arranged bores  39 . 
     Connecting and disconnecting the cooling water inlet or outlet to the casting rollers  21  takes place simultaneously with inserting into or lifting off the roller  21  from the stand  23  or by means of water clamping plates for water and/or multi couplings for the grease supply, energy supply, for the gas supply of, for example, inert gas or air, and for control. 
     For fixation of the stationary axle  21 , a swivel arm  40  is, for example, pivotably connected to the stand  23  on both sides. 
     The configuration of the roller allows a particularly advantageous mounting of an electromagnetic brake  41  within the casting roller  21  between the stationary axle  24  and the rotating casing  27 . 
     The electromagnetic brake is able to calm turbulences of the metal bath, in particular, of the bath surface above the casting gap. The electromagnetic brake is advantageously arranged to be stationary on the stationary axle. 
     In the case of casting rollers  21  for wider strips, the cylindrical casing  27  between the two bearing rings  29 ,  291  can be provided with additional bearing rings for supporting the casing  27  on the stationary axle  24 . These additional bearing rings are also connected to the casing  27  and are radially or axially supported on the axle  24  by ball or roller bearings. 
     FIG. 2 illustrates the casing  27  as a cylindrical body. The casing  27 , without deviating from the inventive subject matter, can also have a slight crown bow or conical shape, and the like. 
     FIG. 3 shows the enlarged detail of a side of the casting roller  1 . Here, the cooled casing is configured of two parts. The casing part  27 ′ comprising the hot casing roll barrel is cooled by means of axially extending bores  39  carrying cooling means. The other casing part  27  form together with a supporting element  29 ′ a nuitary part. Both casing parts  27 ,  27 ′ are abvantageously connected with each other by way of electron-beam welding. The casing part  27  or its supporting element  29 ′ is rotatably supported on the stationary axle  24  by means of the bearing elements  31 . The drive of the casting roller configured in this way is preferably effected by a brushless annular torque motor  36  arranged directly on the axle  24 . The inlet and outlet means  30  for cooling medium, drilled into the axle  24 , are also clearly shown. The other side of the casting roller, which is not shown, is configured correspondingly with or without a drive.