Точність регулювання товщини прокату в умовах високочастотних збурень з урахуванням швидкодії натискних пристроїв

Abstract

In the continuous mills, where the strip thickness at the entrance contains a high-frequency component caused by the eccentricity of the rolls of the previous cage, the effectiveness of AGC-systems for regulating the thickness of the rolled product depends on the speed of operation of hydraulic roll setting devices (HRSD). Analytical substantiation of the transfer functions of the AGC-system by the eccentricity of the rolls and by the thickness of the undercut, taking into account the real speed of the HRSD has been carried out. The frequency characteristics of the AGC-system are analytically determined. It has been proven that with the available speed of the HPD in the interval of rotation frequencies of the support rolls inherent in cold rolling (ω= 5 – 15 s-1), the amplitude-frequency characteristic (AFC) of the AGC-system is almost linear. AFC depending on the time constant T of the HRSD and the ratio of the modulus of rigidity of the rolling strip MΠ to the modulus of rigidity of the rolling stand МK varies within wide limits from A(5)=0.05 (at ω = 5s-1; T=0.01 s; MΠ/MK = 1) to A(15)=0.48 (at ω = 15 s-1; T = 0.01 s; MΠ/MK = 4). At the same time, the thickness variation at the outlet of the cage meets the requirements for thin cold-rolled products of high precision. It has been proved that under the conditions of regulation of the thickness of the rolling strip according to the AGC-algorithm the amplitude of the oscillations of the rolled thickness caused by the eccentricity of the rolls is smaller than the amplitude of the oscillations of the roll gap caused by the eccentricity and decreases with an increase in the rotation frequency of the rolls and the time constant of the HRSD according to a close to linear law. Such linearity creates the basis for the application of adaptive algorithms for determining the actual amplitude of fluctuations of the roll gap in automated systems for compensating the eccentricity of the rolls.