Method for setting different cooling curves of rolling material over the strip width of a cooling stretch in a hot-strip mill or heavy-plate mill

Abstract

A method for setting different cooling rates of metal strips or metal plates (rolling material) over the strip width of a cooling stretch in a hot-strip mill or heavy-plate mill is presented. According to the method, for the calculation of the cooling rate, the initial enthalpy distribution over the material width of the rolling material before the cooling is determined. Proceeding therefrom, a target enthalpy distribution is determined in the width direction and length direction of the rolling material while taking into account a calculation of the flatness and the mechanical properties by means of a microstructure model. Subsequently, the coolant amount and the coolant curve of the cooling stretch are set.

Claims

1.-8. (canceled)

9. A method for setting a cooling curve of metal strips or metal plates (rolling material) over a strip width of a cooling stretch in a hot-strip mill or heavy-plate mill or cooling in a continuous annealing/heat treatment line, comprising: determining an initial enthalpy distribution over the material width of the rolling material before cooling; determining, based on the initial enthalpy distribution, a target enthalpy distribution in the width and length direction of the rolling material while taking into account a calculation of the flatness and/or the mechanical properties by a microstructure model; and subsequently setting a coolant amount and the coolant curve of the cooling stretch.

10. The method according to claim 9, wherein, starting from the initial enthalpy distribution, the target enthalpy distribution is set inhomogeneously over the width.

11. The method according to claim 10, further comprising: dynamically changing the initial enthalpy distribution during the strip run; and accordingly and subsequently recalculating the coolant amount.

12. The method according to claim 11, wherein a control system dynamically changes the target enthalpy distribution in the rolling material over the width during the rolling material run.

13. The method according to claim 12, wherein the enthalpy calculation is based on Gibbs energy.

14. The method according to claim 13, wherein, for the determination of Gibbs energy, databases in the SGTE (Scientific Group on Thermodata Europe) are used, in order to specify the microstructural constituents in the rolling material, and wherein the cooling is regulated and controlled to a constant microstructural phase fraction homogeneously distributed over the strip width of the rolling material as a function of the target enthalpy distribution.

15. The method according to claim 14, wherein an immediate comparison with the mechanical properties calculated in the microstructure model is made via a measuring point and, as a result, a possible deviation of the target enthalpy distribution is corrected immediately by activating or deactivating the cooling.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0016] FIG. 1 is a schematic illustration of the system and the flow concept.

[0017] FIG. 2 is an illustration of the inflowing enthalpy distribution (upper image),

[0018] FIG. 2a shows the target enthalpy distribution (middle image), and

[0019] FIG. 2b shows the difference of the two enthalpy distributions viewed over the width of the rolling material.

[0020] FIG. 3 is an illustration of possible target distributions for the mechanical properties, and

[0021] FIG. 3a shows the flatness viewed over the width.

DETAILED DESCRIPTION

[0022] FIG. 1 schematically shows a part of a possible hot-strip line or heavy-plate line for processing metal strips and/or metal plates. A measuring device 2 is arranged downstream of the last stand 1 of the hot-strip line or heavy-plate line. The measuring device 2 can be a flatness roller or the like, and is located upstream of the actual cooling stretch 3. The measuring device records an actual value of the rolling material 6 upstream of the cooling stretch 3.

[0023] The cooling stretch 3 can include laminar cooling or amplified cooling or compact cooling. Downstream of the cooling stretch 3, at least one further measuring device 4, for example a flatness roller or similar, is arranged to measure the actual value, for example the flatness, of the hot strip/rolling material 6 after it has passed through the cooling stretch 3.

[0024] A computer model 5 receives the measured data from the measuring devices 2 and 4 and specifies cooling medium amounts of the cooling stretch 3 to be used accordingly for setting the target enthalpy distribution. In this way, it can be ensured quasi online that the desired qualities of the rolling material/hot strip 6 may be adjusted and then can be immediately wound up into a coil 7 for further processing. Other units, for example, more measuring devices, descalers, thermal insulation hoods, shears, etc., may be arranged in the region upstream and downstream of the cooling 3.

[0025] FIGS. 2, 2a, 2b illustrate the enthalpy distribution in the hot strip as viewed over the width at the beginning of the recording and at the end of the recording, along with the difference of both enthalpies at beginning and end.

[0026] FIG. 3 illustrates the mechanical properties of yield strength and tensile strength (Rp and Rm) over the width of the hot strip. FIG. 3a illustrates the flatness of the rolling material as viewed over the width.

REFERENCE SIGNS

[0027] 1 Last stand

[0028] 2 Measuring device upstream of the cooling stretch

[0029] 3 Cooling stretch

[0030] 4 Measuring device downstream of the cooling stretch

[0031] 5 Model (calculation model)

[0032] 6 Rolling material/hot strip

[0033] 7 Coil/reel