Study on the chatter vibration of a steel plate mill based on second order cyclic autocorrelation demodulation

Chatter vibration generated during the steel rolling process not only seriously limit the mill performance, but also degrade the surface quality of the steel plate. By analysing the vibration signals from a steel plate mill, Sendzimir 20-high mill, a frequency modulation phenomenon can be observed in the mill chatter vibration signal. In order to monitor and control the chatter vibration during the steel rolling process, an algorithm based on the second order cyclic autocorrelation demodulation is proposed to extract the mill chatter vibration signal. The algorithm is the coupling of frequency analysing, band-pass filtering, second order cyclic autocorrelation calculation and envelope analysing method, and the results of chatter mark vibration can be shown as the waveform in sliced into time domain (SITD) and sliced into frequency domain (SIFD). The experimental results have shown that the modulation frequency is close to the rotational frequency of the intermediate rolls, and it is also shown that mill chatter mark vibration could be evaluated by monitoring the amplitude of the demodulated component whose frequency is close to the rotational frequency of the second intermediate rolls.