Active Vibration Control of a Paper Machine Roll

In process machines unexpected vibration behaviour may cause severe problems when passing the resonance frequencies. In paper machines it is often impossible to avoid sub-critical rotation speeds because of great number of different type of rolls and continuously changing process parameters. Uneven moment of inertia of the rotor and second harmonic of rotational error motion of the bearings are the main reasons for the second harmonic response at critical frequency which often restricts the running speed of a paper machine. By using active vibration control better runnability, less quality variation of paper and increased life time of roll covers and bearings could be achieved.