Rolling mills are prone to many different vibration phenomena, especially when rolling high-strength steels in combination with thin product gauges and high rolling speeds. These vibrations can have a significant impact on quality and productivity in cold-rolling mills. The most destructive form of mill vibration, termed “third-octave chatter,” occurs in a frequency range between 90 and 150 Hz. It is a self-excited vibration, meaning that once it starts, it can grow quickly and result in unstable and uncontrollable rolling conditions.
The ChatterBlock solution is a unique anti-chatter system that fully eliminates third-octave gauge chatter in cold-rolling mills. It is based on an in-depth root-cause analysis of the chatter phenomenon. During this analysis, the Primetals Technologies specialists found that mill chatter represents a process parameter-excited instability generated in the roll gap. The solution thus required a stabilizing system that would bring the rolling mill back into a stable and controllable state. The core function needed was the exertion of a damping effect on the powerful roll-force cylinders that would not hamper the mill’s automatic gauge-control system. Primetals Technologies therefore developed customized controller algorithms, completely new and highly dynamic servovalves, and hydraulic design solutions to control vibration frequencies between 90 and 150 Hz.
Results show that a 10% increase in maximum mill speed is possible, which translates into an impressive increase in plant productivity. ChatterBlock Control is available as an autonomous technology package that can be modified to meet the individual vibration-solution requirements of both new and existing mills. Through the suppression of unwanted mill vibration, producers also benefit from prolonged equipment lifetime, improved product quality and higher profit margins.