DE102005042837A1 - Method for thickness control during hot rolling - Google Patents

Abstract

In the case of a method for regulating the thickness during rolling, in particular during hot rolling with at least one roll stand, the current, mean position of the positioning cylinders of the roll stand and the total rolling force thereof being taken into account, at least one additional position measurement is carried out by determining position signals in the nearer area of the roll gap of the roll stands .

Description

The The invention relates to a method for thickness control during rolling, in particular during hot rolling with at least one roll stand, wherein et al the current, middle position of the adjusting cylinder of the roll stand and the cumulative rolling force of the same are taken into account.

• a) ein Signal erzeugt wird, das ein Maß für die Dicke G5 ist, die durch den Schnittpunkt einer geeigneten Walzendehnungskurve und einer geeigneten Werkstückverformungskurve für den Reduziervorgang festgelegt ist,
• b) ein Signal erzeugt wird, das ein Maß für eine Dicke G3 darstellt, die durch den Schnittpunkt der Kurve für die gemessene Kraft und die Walzendehnungskurve festgelegt ist,
• c) ein Signal erzeugt wird, das ein Maß für einen Unsicherheitsbereich darstellt, der durch die Differenz zwischen den Dicken G5 und G3 darstellenden Signalen bestimmt ist,
• d) ferner ein Signal erzeugt wird, das ein Maß für einen berechneten Streckungsfehler darstellt, indem das den Unsicherheitsbereich darstellende Signal als eine Funktion der für den Reduzierdurchgang vorausbestimmten Dickenabnahme, der für den Reduziervorgang vorausgesagten Walzendehnung und der relativen Fehlerwahrscheinlichkeit sowohl bei der Vorausbestimmung der Dickenabnahme als auch der Dehnung verändert wird, und
• e) ein Signal erzeugt wird, das ein Maß für die berechnete Dicke G1 ist, indem das die Dicke G3 darstellende Signal zu dem berechneten Dehnungsfehler hinzuaddiert wird.

From the DE 20 20 402 is a method for calculating the thickness G1 of thin, hard workpieces after a reduction pass through a reduction rolling line with opposed rolling surfaces, and a measuring device for measuring the surface breaking forces, which are generated during passage of the workpiece through the opposed rolling surfaces during a Reduziervorganges, in the :

• a) a signal is generated which is a measure of the thickness G5 defined by the intersection of a suitable roll elongation curve and a suitable workpiece deformation curve for the reduction process,
• b) generating a signal representing a measure of a thickness G3 defined by the intersection of the measured force curve and the roll elongation curve;
• c) generating a signal representing a measure of an uncertainty range determined by the difference between the thicknesses G5 and G3 representing signals,
• d) further generating a measure indicative of a calculated stretch error by expressing the signal representing the uncertainty region as a function of the reduction predicted for the reduction pass, the rolling strain predicted for the reduction, and the relative error probability in both the prediction of the thickness decrease also the elongation is changed, and
• e) generating a signal indicative of the calculated thickness G1 by adding the signal representing the thickness G3 to the calculated strain error.

In the DE 26 57 455 A1 is described a method for compensating the roll deformation on controllable prestressed rolling stands, in which the strip thickness is controlled by hydraulic actuators, and in which by hydraulic biasing cylinder, the contact force (F _a ) as the sum of rolling force and controllable biasing force according to the equation F a = (F a0 + (F r - F r0 )) · C a / (C i + c a ) is changed such that to the basic setpoint (F _a0 ) of the adjusting force an additional full value is added, which is formed from the difference between the actual value (F _r ) of the biasing force and initial value (F _r0 ) of the biasing force and with the ratio (c _a / (c _i + c _a )) of the spring stiffness (c _a ) of the outer frame part to the sum of the spring stiffness of the inner (c _i ) and outer frame part (c _a ) is evaluated.

From the DE 16 02 195 A1 For example, a method of calculating the thickness of thin hard workpieces is known.

That a signal is generated which is a measure of the thickness G5 defined by the intersection of a suitable roll elongation curve and a suitable workholding curve for the reduction operation;
generating a signal indicative of a thickness G3 defined by the intersection of the measured force curve and the roll elongation curve,
generating a signal representing a measure of an uncertainty region determined by the difference between the thicknesses G5 and G3 representing signals,
further generating a signal representative of a calculated stretch error by varying the signal representing the uncertainty region as a function of the rolling strain predicted for the reduction pass and the relative error probability in both the prediction of thickness reduction and elongation, and
a signal is generated which is a measure of the calculated thickness G1 by adding the signal representing the thickness G3 to the calculated strain error.

So far, the so-called Gaugemeterprinzip used to determine the current strip thickness for the thickness control during hot strip rolling. For this purpose, the measured position S _DS , S _{OS of} the adjusting cylinder is corrected by the calculated gantry strain g (see also FIG 1 ). The gantry expansion g is calculated using the measured rolling force F _DS , F _OS and a gantry expansion curve 1 / M _G. The thus determined strip thickness is then compared with the thickness setpoint and compensated. For this process, apart from the measurements of position and rolling force, an exact framework model is required.

At the Rolls of hard grades and thin ribbons carry small ones Inaccuracies in the framework model to relatively large Defects in the strip thickness and possibly the instability of the thickness control.

The invention is therefore the task To improve a method of the type described above such that the above-mentioned disadvantages are avoided.

These Task is inventively characterized solved, that the framework expansion share is minimized. This happens because at least one additional Position measurement by determination of position signals in the nearer area of the Rolling nip of the rolling stands carried out becomes. In particular, the position signals between the Work rolls and / or the backup rolls and / or the work roll chocks and / or the backup roll chocks consider / to determine.

The advantage of the method according to the invention is that the position measurement contains a smaller amount of framework expansion. So only the roll flattening and the roll bending are to be considered. Other parts, such as the elongation of the uprights and the crossheads, need not be calculated. Especially when measuring the distance of the work roll chocks, the slurry of the Morgoil bearings, the bending of the backup rolls and the support roll eccentricities need not be taken into account. As in 2 In addition, the thickness control method known from the prior art is still used completely and improved or expanded by the features described above.

The inventive method leads to a more accurate determination of the strip thickness for hard grades and improves specifically during thin strip rolling the dynamic behavior of the thickness control.

In a further development the signals obtained also for position control and / or for swivel control and / or for calculating the strip thickness and thus for regulating the Band thickness can be used.

One embodiment The invention will be described in more detail with reference to schematic drawings. Show it:

1 a flowchart for the thickness control according to the prior art and

2 a flow chart for thickness control according to the invention.

In 1 is a flow chart for the known thickness control during rolling, especially during hot rolling, shown. An existing example of a pair of work rolls AW and a pair of support rollers SW rolling stand W has an operating side OS and a drive side DS. A strip B is located between the pair of work rolls AW. In the known method for thickness control, the cylinder position of the operating side S _OS and the cylinder position of the drive side S _{DS are} determined and the current, mean cylinder position S _ACT determined. Furthermore, the sum rolling force F _ACT is determined by determining the rolling force operating side F _OS and the rolling force driving side F _DS . The gantry expansion g is calculated by means of the total rolling force F _ACT and a gantry expansion curve 1 / M _G.

The actual band thickness h _ACT is determined by measuring the current, central cylinder position S _ACT and the calculated gantry strain g.

The actual strip thickness h _ACT is compared with the strip thickness set point h _REF and used for thickness control. The thickness controller supplies the position setpoint for the cylinder position control.

According to the invention, the known thickness control according to the flowchart after 2 improved. For this purpose, for example, the distance of the work roll chocks on the operating side S _ROS and measured on the drive side S _RDS and then the average distance of the work roll chocks S _R determined. The further determined value for the current, average cylinder position S _ACT is compared directly with the cylinder position _setpoint S _REF .

The likewise determined values of the rolling force operating side F _OS and the rolling force drive side F _DS lead to the total rolling force F _ACT . These are inventively combined with a scaffold module M _R , which is based on the work roll chocks, and then the gantry strain g _R determined. The scaffold module M _R depends according to the invention on the selected position measurement. The position measurement position signals to be taken into account for the method, wherein at least one position signal is required, are determined between the work rolls AW and / or the backup rolls SW and / or the work roll chocks and / or the backup roll chocks. The framework strain to be taken into account in the method according to the invention is to be matched in each case to the location of the position signal obtained.

The distance on the operating side S _ROS and the distance on the drive side S _RDS lead to the average distance of the example work roll chocks S _R. From the distance of the work roll chocks S _R and the frame stretch based on the work roll chocks g _R the actual tape thickness h _{ACT is} determined and compared with the band thickness setpoint h _REF and compensated.

AW

Stripper

SW

supporting roll

W

rolling mill

B

tape

DS

driving side

OS

operating side

F _ACT

Total rolling force

F _OS

rolling force operating side

F _DS

rolling force driving side

S _ACT

current, middle cylinder position

S _OS

cylinder position operating side

S _DS

cylinder position driving side

S _REF

Cylinder position setpoint

h _ACT

current strip thickness

h _REF

Strip thickness target value

S _R

middle Distance of the work roll chocks

S _ROS

distance operating side

S _RDS

distance driving side

g _R

mill stretch based on work roll chocks

M _R

scaffold Model based on work roll chocks

G

mill stretch

M _G

stand modulus

Claims (5)

Method for thickness control during rolling, in particular during hot rolling with at least one roll stand, wherein, inter alia, the current, middle position of the setting cylinder of the roll stand and the sum rolling force thereof are taken into account, characterized in that at least one additional position measurement by determining position signals in the nearer region of the roll gap Rolling stands is performed. Method according to claim 1, characterized in that that the position signals between the work rolls and / or the backup rolls and / or the work roll chocks and / or the backup roll chocks become. Method according to claim 1 or 2, characterized that the position signals are used for position control. Method according to one of claims 1 to 3, characterized that the position signals are used for the swivel control. Method according to one of claims 1 to 4, characterized that the position signals used to calculate the strip thickness become.