The invention concerns a method for automatic gage control during rolling, especially hot rolling, with at least one rolling stand, where factors that are considered include the present mean position of the adjustment cylinders of the rolling stand and their total rolling force.
DE 20 20 402 discloses a method for calculating the gage G1 of a thin, hard workpiece after a reducing pass through a reducing mill train with opposing rolling surfaces and a measuring instrument for measuring the roll separating forces, which are produced during the passage of the workpiece through the opposing rolling surfaces during a reducing operation, in which
(a) a signal that is a measure of the gage G5 is generated, which is determined by the point of intersection of an appropriate mill stretch curve and an appropriate workpiece deformation curve for the reducing operation,
(b) a signal that is a measure of a gage G3 is generated, which is determined by the point of intersection of the measured force curve and the mill stretch curve,
(c) a signal that is a measure of a range of uncertainty is generated, which is determined by the difference between signals representing the gages G5 and G3,
(d) a signal that is a measure of a calculated stretch error is generated by varying the signal that represents the range of uncertainty as a function of the draft predicted for the reducing pass, of the mill stretch predicted for the reducing pass, and of the relative probability of error in predicting both draft and mill stretch, and
(e) a signal that is a measure of the calculated gage G1 is generated by adding the signal that represents the gage G3 to the calculated stretch error.
DE 26 57 455 A1 describes a method for compensating roll deformation in rolling stands with prestressing that can be automatically controlled, in which the strip thickness is automatically controlled by hydraulic actuators, and in which the contact force (Fa), which is the sum of the rolling force and the automatically controllable prestressing force according to the following equation:
F
a=(Fa0+(Fr−Fr0))*ca/(ci+ca),
is varied by hydraulic prestressing cylinders in such a way that, to the base set value (Fa0) of the contact force, a supplementary set value is added, which is formed from the difference between the actual value (Fr) of the prestressing force and the initial value (Fr0) of the prestressing force and is evaluated with the ratio (ca/(ci+ca)) of the spring stiffness (ca) of the outer part of the stand to the sum of the spring stiffness (ci) of the inner part of the stand and the spring stiffness (ca) of the outer part of the stand.
DE 16 02 195 A1 discloses a method for calculating the gage of thin, hard workpieces, in which
Until now, the so-called gage meter principle for determining the present strip gage has been used for automatic gage control during hot strip rolling. To this end, the measured SDS, SOS of the adjustment cylinders is corrected by the calculated mill stretch g (see also
In the rolling of hard materials and thin strip, small inaccuracies in the mill model lead to relatively large errors in the strip gage and sometimes instability of the automatic gage control system.
Therefore, the objective of the invention is to improve a method of the type described above in such a way that the disadvantages specified above are avoided.
In accordance with the invention, this objective is achieved by minimizing the mill stretch component. This is accomplished by carrying out at least one additional position measurement by detecting position signals in the immediate vicinity of the roll gap of the rolling stands. In this connection, especially the position signals between the work rolls and/or the backup rolls and/or the work roll chocks and/or the backup roll chocks are to be considered/detected.
The advantage of the method of the invention is that the position measurement contains a smaller mill stretch component. Thus, only the roll flattening and the roll bending are to be considered. Other components, such as the expansion of the columns and the crossheads, do not have to be considered. Specifically in the measurement of the separation of the work roll chocks, the suspension of the Morgoil bearings, the bending of the backup rolls, and backup roll eccentricities do not have to be taken into consideration. As shown in
The method of the invention results in a more exact determination of the strip gage in the case of hard materials and, especially in the case of thin strip rolling, improves the dynamic behavior of the automatic gage control system.
In a further development of the invention, the signals that are obtained can also be used for automatic position control and/or for automatic swivel control and/or for calculation of the strip gage and thus for automatic control of the strip gage.
A specific embodiment of the invention is described in greater detail below with reference to the accompanying schematic drawings.
In accordance with the invention, the prior-art automatic control system is improved as shown in the flowchart in
The values of the rolling force on the operating side FOS and the rolling force on the drive side FDS also continue to be determined and lead to the total rolling force FACT. These are combined, in accordance with the invention, with a mill modulus MR with respect to the work roll chocks, and then the mill stretch gR with respect to the work roll chocks is determined.
In accordance with the invention, the mill modulus MR depends on the selected position measurement. The position signals of the position measurement that are to be taken into consideration for the method, with at least one position signal being 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 mill stretch to be taken into consideration in the method of the invention is to be coordinated with the given site of the position signal that is obtained.
The separation on the operating side SROS and the separation on the drive side SRDS lead to the mean separation of the work roll chocks SR, for example. The present strip gage hACT is determined from the separation of the work roll chocks SR and the mill stretch with respect to the work roll chocks gR and is then compared with the strip gage set value hREF and automatically controlled.
Number | Date | Country | Kind |
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10-2005-040-690.4 | Aug 2005 | DE | national |
10-2005-042-837.1 | Sep 2005 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP2006/007249 | 7/24/2006 | WO | 00 | 2/14/2008 |