Soft Nip Calender Barring - Self Excited
Vibration Causes Excessive Maintenance
nip soft nip calenders also suffer from barring, resulting in caliper
variations and increased roll maintenance. This is also a self-excited
vibration with two possible feedback paths, both involving the soft
cover. The feedback can be temperature induced cover property
creep in the cover causing minute diameter variations.
The vibration will usually show itself as a barring problem. The barring frequency is always at or close to a
resonance in the calender stack or rolls. The resonance is
excited by an integer number of bars around the circumference of the
determine the problem, calender vibration and temperature measurements
are made. When required these are augmented with modal
measurements to determine
the resonances within the stack. Finite element calculations are
used when redesign is required.