Casting-rolling integrated plant and method for producing a hot strip with a final thickness < 1.2 mm on the casting-rolling integrated plant

Abstract

A combined casting and rolling installation that produces hot-rolled strip with a final thickness<1.2 mm, and includes a first continuous casting installation and a second continuous casting installation, each producing slabs from liquid steel; a slab manipulator that conveys the slabs into a walking beam furnace that conveys the slabs into a rolling installation and heats the slabs to rolling temperature. The rolling installation includes a rough rolling mill forming rough-rolled strips from the heated slabs; a coil box forming a coil from the rough-rolled strip and unwinding the rough-rolled strip; a joining device forming an endless rough-rolled strip by connecting its ends without filler material; a multi-stand finishing rolling mill finish-rolling the endless rough-rolled strip to form a finished strip with the final thickness; a cooling section forming the hot-rolled strip; and a plurality of coiling devices coiling the hot-rolled strip.

1 . A combined casting and rolling installation for producing hot-rolled strip with a final thickness<1.2 mm, preferably≤1.0 mm, comprising:
 at least a first continuous casting installation and a second continuous casting installation, wherein each continuous casting installation casts liquid steel into slabs; 
 a slab manipulator for conveying the slabs from the continuous casting installations into a walking beam furnace, 
 the walking beam furnace conveying the slabs from the slab manipulator into a rolling installation and heating the slabs to rolling temperature, wherein slabs from the first continuous casting installation and slabs from the second continuous casting installation pass completely through the walking beam furnace and are uniformly heated in the process; 
 the rolling installation, comprising, 
 a rough rolling mill for rough rolling the heated slabs to form a rough-rolled strip, 
 a preferably thermally insulated coil box for winding up the rough-rolled strip to form a coil and for unwinding the rough-rolled strip, 
 a joining device for connecting, without filler material, a foot of a leading rough-rolled strip to a head of a trailing rough-rolled strip to form an endless rough-rolled strip, 
 a multi-stand finishing rolling mill for finish rolling the endless rough-rolled strip to form a finished strip with the final thickness, 
 a cooling section for cooling the finished strip to form the hot-rolled strip, and 
 a plurality of coiling devices for coiling the hot-rolled strip, wherein the roughing rolling mill, the coil box, the joining device, the multi-stand finishing rolling mill the cooling section and the coiling devices of the rolling installation are arranged in-line one behind the other, and the first continuous casting installation has a first offset in a first direction with respect to the rolling installation and the second continuous casting installation has a second offset in the first direction with respect to the rolling installation. 
 
     
     
         2 . The combined casting and rolling installation as claimed in  claim 1 , wherein the continuous casting installations are configured to generate slabs with a thickness of 140 to 240 mm and a width of between 1100 and 2300 mm. 
     
     
         3 . The combined casting and rolling installation as claimed in  claim 1 , wherein the roughing rolling mill is a reversing, preferably one-stand, roughing rolling mill. 
     
     
         4 . The combined casting and rolling installation as claimed in  claim 1 , wherein the first direction is the horizontal. 
     
     
         5 . The combined casting and rolling installation as claimed in  claim 1 , wherein the finishing rolling mill comprises five to seven finishing roll stands. 
     
     
         6 . The combined casting and rolling installation as claimed in  claim 1 , wherein a first descaling device is arranged downstream of the walking beam furnace and upstream of the roughing rolling mill, and/or in that a second descaling device is arranged upstream of the joining device and a third descaling device is arranged upstream of the finishing rolling mill. 
     
     
         7 . The combined casting and rolling installation as claimed in  claim 1 , wherein the slab manipulator can discharge slabs generated by the continuous casting installations transversely with respect to the conveying direction from the continuous casting installations to the walking beam furnace, and the slab manipulator can introduce slabs which have not been generated in the continuous casting installations of the combined casting and rolling installation transversely with respect to the conveying direction from the continuous casting installations to the walking beam furnace. 
     
     
         8 . A method for producing a hot-rolled strip with a final thickness<1.2 mm, preferably ≤1.0 mm, on a combined casting and rolling installation, in particular as claimed in one of the preceding claims, comprising the following steps:
 continuously casting liquid steel into slabs on at least a first continuous casting installation ( 1   a ) and a second continuous casting installation; 
 conveying the slabs from the continuous casting installations into an inlet region of a walking beam furnace; 
 conveying the slabs from the inlet region through the walking beam furnace into an outlet region of the walking beam furnace, wherein the slabs are heated to rolling temperature; 
 rough rolling the heated slabs to form a rough-rolled strip; 
 winding up the rough-rolled strip to form a coil and preferably thermally insulating, particularly preferably heating, the coil; 
 unwinding the rough-rolled strip from the coil; 
 connecting, without filler material, a foot of a leading rough-rolled strip to a head of a trailing rough-rolled strip to form an endless rough-rolled strip; 
 finish rolling the endless rough-rolled strip to form a finished strip with the final thickness by way of multiple rolling passes in a multi-stand finishing rolling mill; 
 cooling the finished strip to form the hot-rolled strip; 
 cutting the hot-rolled strip; and 
 coiling the hot-rolled strip. 
 
     
     
         9 . The method as claimed in  claim 8 , wherein the rough rolling is effected by way of multiple, preferably 3-5, rolling passes in a reversing roughing rolling mill. 
     
     
         10 . The method as claimed in  claim 8 , wherein when connecting the rough-rolled strips to form the endless rough-rolled strip, the foot of the leading rough-rolled strip is firstly overlapped with a head of the trailing rough-rolled strip, and then the overlapping region of the rough-rolled strips is compressed, wherein the vertical positions of the rough-rolled strips are aligned with one another. 
     
     
         11 . The method as claimed in  claim 8 , wherein the rough-rolled strips are descaled after the unwinding and prior to the connecting. 
     
     
         12 . The method as claimed in  claim 8 , wherein the slabs have a thickness of 140 to 240 mm and a width of between 1100 and 2300 mm, and/or the rough-rolled strip has a thickness of between 25 and 35 mm. 
     
     
         13 . The method as claimed in  claim 8 , wherein the slabs are charged at a temperature≥900° C. into the walking beam furnace. 
     
     
         14 . The method as claimed in  claim 8 , wherein the combined casting and rolling installation has an annual production capacity of between 3 and 6 million tons, in particular between 3.5 and 5.5 million tons. 
     
     
         15 . The method as claimed in  claim 8 , wherein the continuous casting installations produce slabs with a thickness of 150 to 190 mm at a casting rate of 4 to 5 m/min and slabs with a thickness of 191 to 230 mm at a casting rate of 2 to 4 m/min.