Frequency Modulation of High-Speed Mill Chatter

摘要

Mill chatter is a notorious condition in high-speed strip rolling process, whose behaviour is complexrnand changeful. During a fieldwork to measure the vibration in high-speed rolling mills, a frequency modulationrnphenomenon was identified, which had not been reported in strip rolling community. This article makes arntheoretical investigation to the newly encountered phenomenon in strip rolling process. According to an analysisrnof the mill roller bearings, the periodic change of stiffness of roller bearings at the fixed load orientation, togetherrnwith the periodic change of the effective errors of the bearings, may cause amplitude and frequency modulation，rnbased on the theories of Fourier series and Bessel function. The comparison between test results and theoreticalrnanalysis implies that the frequency modulation is caused by the effective errors of the mill roller bearings thatrnhave 12 ripples on the internal ring of the bearings.