Casting-rolling integrated plant for producing a hot-rolled finished strip from a steel melt

Abstract

A casting-rolling integrated plant that is capable of producing, from a steel melt, in a cost-effective manner and with high productivity, a hot-rolled finished strip having a thickness of 0.6 mm, an excellent flatness, and an excellent profile by dividing the thickness reduction into at least three stages (roughing, intermediate and finishing train), measuring the actual profile after the roughing, intermediate and finishing train, and equipping the stands in the roughing, intermediate and finishing train with actuators for influencing the strip profile and/or the strip flatness.

Claims

1. A casting-rolling integrated plant for producing a hot-rolled finished steel strip, comprising: a continuous casting plant having an arcuate strand guide for the continuous casting of a steel melt to form a continuous strand having a slab or thin slab cross section; a roughing train having a plurality of roughing stands (R1 . . . R3) for roughing the continuous strand to form a roughed strip, wherein at least one roughing stand has at least one actuator for setting profile and/or flatness of the roughed strip; a first induction furnace for heating the roughed strip to a first rolling temperature; a first measuring device for measuring an actual profile of the roughed strip, wherein the first measuring device is arranged between last roughing stand (R3) of the roughing train and the first induction furnace in material flow direction; a first descaling device for descaling the heated roughed strip; an intermediate train having a plurality of intermediate rolling stands (I1 . . . I3) for intermediate rolling of the continuous roughed strip to form an intermediate strip, wherein at least one intermediate rolling stand has at least one actuator for setting profile and/or flatness of the intermediate strip; a second measuring device for measuring an actual profile of the intermediate strip and an actual flatness of the intermediate strip; a finishing train having a plurality of finish rolling stands (F1 . . . F3) for finish rolling the continuous intermediate strip to form a finished strip, wherein at least one finish rolling stand has at least one actuator for setting profile and/or flatness of the finished strip; a third measuring device for measuring an actual profile of the finished strip and an actual flatness of the finished strip; a second induction heater arranged to heat an intermediate strip received from the intermediate train, and feeding the heated intermediate strip to the finishing train directly; shears for transversely dividing the finished strip; a coiling device having at least two coiler drums for coiling the finished strip into coils; a first profile controller that controls the at least one actuator of the at least one roughing stand in the roughing train as a function of the actual profile of the roughed strip in such a way that the actual profile of the roughed strip corresponds as far as possible to a setpoint profile; a second profile controller that controls the at least one actuator of the intermediate rolling stand in the intermediate train as a function of the actual profile of the intermediate strip in such a way that the actual profile of the intermediate strip corresponds as far as possible to a setpoint profile; a first flatness controller that controls the at least one actuator of the intermediate rolling stand in the intermediate train as a function of measured actual flatness of the intermediate strip in such a way that actual flatness of the intermediate strip corresponds as far as possible to a setpoint flatness; a third profile controller that controls the at least one actuator of the at least one finish rolling stand in the finishing train as a function of the actual profile of the finished strip in such a way that the actual profile of the finished strip corresponds as far as possible to a setpoint profile; and a second flatness controller that controls at least one actuator in the finishing train as a function of the measured actual flatness of the finished strip in such a way that actual flatness of the finished strip corresponds as far as possible to a setpoint flatness, wherein the second profile controller and the first flatness controller are active and have outputs thereof superimposed on one another in order to control the actual profile and the actual flatness in the intermediate train, and wherein the third profile controller and the second flatness controller are active and have outputs thereof superimposed on one another in order to control the actual profile and the actual flatness in the finishing train.

2. The casting-rolling integrated plant as claimed in claim 1, wherein the second measuring device is arranged between the last intermediate rolling stand (I3) of the intermediate train and the first finish rolling stand (F1) of the finish rolling train in the material flow direction.

3. The casting-rolling integrated plant as claimed in claim 1, wherein at least one finish rolling stand (F1 . . . F3) of the finishing train has two displacement devices for axial displacement of working rolls of the at least one finish rolling stand in opposite directions.

4. The casting-rolling integrated plant as claimed in claim 3, wherein the displacement devices allow an axial displacement in a range of 200 mm to 800 mm.

5. The casting-rolling integrated plant as claimed in claim 1, wherein the third measuring device is arranged between the last finish rolling stand (F3) of the finishing train and the coiling device in the material flow direction.

6. The casting-rolling integrated plant as claimed in claim 1, wherein a first temperature profile measuring device for measuring a temperature profile of the roughed strip is arranged between the end of the first induction furnace and the first descaling device, wherein a first temperature controller controls inductors of the first induction furnace in such a way that the temperature profile corresponds as far as possible to a first setpoint profile.

7. The casting-rolling integrated plant as claimed in claim 1, wherein a second temperature profile measuring device for measuring a temperature profile of the intermediate strip is arranged between the end of a second induction furnace and a second descaling device, wherein a second temperature controller controls inductors of the second induction furnace in such a way that the temperature profile corresponds as far as possible to a second setpoint profile.

8. The casting-rolling integrated plant as claimed in claim 1, further comprising a slab descaler for descaling the strand before roughing.

9. The casting-rolling integrated plant as claimed in claim 1, further comprising a cooling section for cooling the finished strip to a coiling temperature.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above-described properties, features and advantages of this invention and the manner in which these are achieved will become more clearly and distinctly understandable in conjunction with the following description of a number of exemplary embodiments, which are explained in greater detail in conjunction with the drawings. In the drawings:

(2) FIG. 1 shows a diagram of a first casting-rolling integrated plant,

(3) FIG. 2 shows a control diagram for a first profile controller in the roughing train 5 of FIG. 1,

(4) FIG. 3 shows a control diagram for a second profile controller in the intermediate train 10 of FIG. 1,

(5) FIG. 4 shows a control diagram for a second flatness controller in the finishing train 11 of FIG. 1,

(6) FIG. 5 shows a diagram of a second casting-rolling integrated plant,

(7) FIG. 6 shows a temperature curve in the production of an ultra-thin finished strip in a casting-rolling integrated plant, and

(8) FIG. 7 shows a thickness curve in the production of an ultra-thin finished strip in a casting-rolling integrated plant.

DESCRIPTION OF THE EMBODIMENTS

(9) FIG. 1 shows a first embodiment of a casting-rolling integrated plant according to the invention. In the continuous casting plant 1, a steel melt is cast into a continuous strand 4 with a slab format and a final thickness of 100 mm. For this purpose, the steel melt is fed to the mold 3 via a tundish 2. The strand 4 leaves the mold with a thickness of 105 mm. In the arcuate strand guide of the continuous casting plant 1, the thickness of the strand 4 is reduced to the final thickness of 100 mm by an LCR. Subsequently, the strand 4 enters the first roughing stand of the roughing train 5 and is reduced to a roughed strip with a thickness of 9 mm by three rolling passes in the roughing train. The last rolling pass in the roughing train 5 takes place at 900 C. The roughed strip is heated to a temperature of 1150 C. in the first induction furnace 8 and then descaled in the first descaling device 9. During this process, the temperature of the roughed strip falls to 1050 C. In the following intermediate train 10, the roughed strip is reduced to an intermediate strip with a thickness of 1.3 mm by three rolling passes. The last rolling pass in the last intermediate rolling stand of the intermediate train 10 takes place at a temperature of 925 C. The intermediate strip is then heated to a temperature of 975 C. in the second induction furnace 8a. Since the heating in the second induction furnace 8a takes place very rapidly and by only 50 C., the heated intermediate strip is not descaled in the second descaling device 9a and enters directly into the first finish rolling stand of the finishing train 11. In the finishing train 11, the roughed strip is reduced, again by three rolling passes, to an ultra-thin finished strip with a thickness of 0.6 mm. The last rolling pass in the finishing train 11 takes place in the austenitic temperature range at a temperature of 875 C. After the finishing train 11, the finished strip is cooled to 650 C. in the cooling section 12, then divided transversely by the shears 13 and coiled in the coiling devices 14. The method takes place continuously, i.e. the continuous strip is transversely divided for the first time by the shears 13. The temperature curves and the thickness curves during the production of the ultra-thin finished strip with a thickness of 0.6 mm are given in FIGS. 6 and 7.

(10) The mode of operation of a first profile controller is explained with reference to FIG. 2. A first measuring device 6 for measuring the actual profile of the roughed strip is arranged downstream of the last roughing stand R3 of the roughing train 5 and upstream of the first induction furnace 8. The measured values m1 for the actual profile of the roughed strip are transmitted to the controller 15. As a function of the measured values m1 for the actual profile and as a function of the setpoint profile of the roughed strip, the controller 15 calculates three manipulated variables u1 . . . u3, which are transmitted to (hydraulic) actuators in the bending blocks for bending the working rolls in the three roughing stands R1 . . . R3 of the roughing train 5. The actuators bend the working rolls of the roughing stands in such a way that the actual profile corresponds as far as possible to the setpoint profile.

(11) The mode of operation of a second profile controller is explained with reference to FIG. 3. A second measuring device 6a for measuring the actual profile of the intermediate strip is arranged downstream of the last intermediate rolling stand 13 of the intermediate train 10 and upstream of the second induction furnace 8a. The measured values m2 for the actual profile are transmitted to the controller 15. As a function of the measured values m2 for the actual profile and as a function of the setpoint profile of the intermediate strip, the controller 15 calculates three manipulated variables u4 . . . u6, which are transmitted to (hydraulic) actuators in the bending blocks for bending the working rolls in the three intermediate rolling stands I1 . . . I3 of the intermediate train 10. The actuators bend the working rolls of the intermediate rolling stands in such a way that the actual profile corresponds as far as possible to the setpoint profile.

(12) The mode of operation of a third profile controller and a second flatness controller are explained with reference to FIG. 4. A third measuring device 6b for measuring the actual profile m3 and the actual flatness m4 of the finished strip is arranged downstream of the last finish rolling stand F3 of the finishing train 11 and upstream of the cooling section. The mode of operation of the third profile controller is similar to the profile controllers already explained. The second flatness controller functions as follows: the measured values m4 for the actual flatness are likewise transmitted to the controller 15. As a function of the measured values m4 for the actual flatness and as a function of the setpoint flatness of the finished strip, the controller 15 calculates three manipulated variables u7 . . . u9, which are transmitted to (hydraulic) actuators in the bending blocks for bending the working rolls in the three finish rolling stands F1 . . . F3 of the finishing train 11. The actuators bend the working rolls of the finish rolling stands in such a way that the actual flatness corresponds as far as possible to the setpoint flatness.

(13) It is possible for there to be actuators for bending the working rolls, e.g. bending blocks, in the finish rolling stands of the finishing train 11 and additionally for there to be width-dependent multi-zone cooling of the working rolls or possibly even of the back-up rolls.

(14) FIG. 5 shows the casting-rolling integrated plant of FIG. 1 with three profile controllers for controlling the profile downstream of the roughing, intermediate and finishing trains 5, 10, 11 and two flatness controllers for controlling the flatness downstream of the intermediate and finishing trains 10, 11. The three profile controllers and the two flatness controllers are combined to form a digital controller 15.

(15) Although the invention has been illustrated and described more specifically in detail by means of the preferred exemplary embodiments, the invention is not restricted by the examples disclosed, and other variations can be derived therefrom by a person skilled in the art without exceeding the scope of protection of the invention.

LIST OF REFERENCE SIGNS

(16) 1, CCM continuous casting plant 2 tundish 3 mold 4 strand 5 roughing train 6 first measuring device 6a second measuring device 6b third measuring device 7 roller table 8, IH1 first induction furnace 8a, IH2 second induction furnace 9, DESC first descaling device 9a second descaling device 10 intermediate train 11 finishing train 12 cooling section 13 shears 14, DC coiling device 15 controller m1 . . . m4 measured variables u1 . . . u9 manipulated variables R1 . . . R3 first to third roughing stand I1 . . . I3 first to third intermediate rolling stand F1 . . . F3 first to third finish rolling stand