Process damping of self-excited third octave mill vibration

A cold-rolling mill, comprising:

• a mill stand having a top work roll and a bottom work roll between which a metal strip can be passed at a rolling speed;
• a tension adjustor positionable upstream of the mill stand for adjusting tension of the metal strip as the metal strip enters the mill stand;
• a sensor positionable on or adjacent the mill stand for detecting vibrations indicative of self-excited third octave vibration;
• and
• a controller coupled to the sensor and the tension adjustor to induce adjustment of the tension of the metal strip in response to detection of the vibrations indicative of self-excited third octave vibration while maintaining the rolling speed.

A method, comprising:

• rolling a metal strip on a mill stand at a rolling speed, wherein the metal strip has an entry tension;
• detecting fluctuations in the entry tension at or above approximately 90 hertz by a sensor positionable on or adjacent the mill stand;
• and
• adjusting the entry tension of the metal strip in response to the detected fluctuations by a tension adjustor positionable upstream of the mill stand while maintaining the rolling speed, wherein adjusting the entry tension comprises using a controller coupled to the sensor and the tension adjustor.