Cold belt rolling mill panel thickness control limited frequency domain feedforward compensation method based on wave function

Abstract

The invention discloses a cold belt rolling mill panel thickness limited frequency domain feedforward control compensation method based on wave function, including the following steps: step one, a measuring device is utilized to measure process information online; step two, calculating is carried out by Psi(p.deltaL, t), wherein p is equal to -N, -N+1,..., N; step three, wavelet decomposition level is determined; step four, a wavelet decomposition method is adopted to decompose a Psi(p.deltaL, td) sequence, thus obtaining low frequency components and detailed components of each level; step five, Psi(p.deltaL, td) is made to be equal to GML(p.deltaL, td)-GMH(p.deltaL, td); step six, setting of cleaning between rolls is adjusted by the obtained Psi(0, td) by a feedforward compensator. The invention adopts the wavelet filtering method to reduce overlap of action range of feedforward and feedback frequency domains in the panel thickness control system, realizes orthogonalization of feedforward and feedback control actions to the utmost extent, reasonably reduces the action range of the feedforward frequency domain, is beneficial to optimization of parameters of the feedforward compensation system, improves the matching efficiency of two basic control manners of feedforward and feedback in the panel thickness control system, and finally can effectively improve panel thickness control precision.

Description

technical field [0001] The invention relates to the technical field of thickness control and compensation, in particular to a feedforward compensation method with a limited frequency domain range of thickness control for cold strip rolling mills. Background technique [0002] In the rolling production of metal plate and strip, the longitudinal thickness accuracy (thickness difference) of the strip is the main quality index. [0003] The accuracy of the longitudinal thickness of the rolled strip is restricted by many factors, among which the fluctuation of the thickness of the inlet strip will seriously affect the accuracy of the outlet thickness. Therefore, modern cold strip mills generally install a thickness gauge and a strip speed measuring device on the inlet side. The interference of the inlet strip thickness fluctuation on the outlet thickness is eliminated by thickness feedforward. [0004] Feedback and feedforward are the two basic methods of strip thickness control...

AI Technical Summary

Problems solved by technology

[0014] (1) Accurate tracking of the position of the strip requires accurate measurement of the instantaneous speed of the strip, but in actual engineering, in order to obtain a high-precision instantaneous speed signal of the strip (such as installing a laser velocimeter), it needs to increase a lot of cost, and the rolling The oil mist generated during the process will also interfere with the laser speed measurement

[0015] (2) The hydraulic servo system used as rolling mill reduction control is nonlinear to the amplitude of the following command change, and its servo following response time has uncertainty

[0020] Although the use of dynamic arrays to track and delay the strip section can accurately calculate the thickness of the strip at the roll gap, it is not a holographic description of the strip thickness tracking in the rolling process and has poor flexibility. Mathematical analysis of process strip thickness is limited

The above measures have reduced the overlapping of the feedforward and feedback frequency domain ranges in the plate thickness control system to a certain extent, but did not give a method to determine the frequency range of the feedforward control, and the relevant control parameters cannot be modified online, which makes the In practical applications, it is impossible to optimize the design of the feed-forward filter, but to adopt conservative filter parameters based on experience

Reducing the strength of feedforward compensation can reduce the requirement for the accuracy of instantaneous speed measurement, but it is at the expense of compensation accuracy

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