Joint Time Frequency Analysis

Application
Variable speed paper finishing equipment, like offline calenders and winders, accelerate from a stopped condition to full operating speed in a matter of a few minutes. During this period vibrations in the many rolls and rotating components change with speed. At certain speeds, the vibrations in rolls may increase significantly as resonance frequencies are approached and passed, thereby affecting paper quality and runnability.
JTFA is a speed dependent analysis of vibrations in paper finishing equipment, or any equipment whose speed is rapidly changing. Using the high-speed processing power of the Sensodec 6S and its unique simultaneous multi-channel measurements, the vibration signals and spectra of all rotating equipment in the machinery are anlyzed. Vibration specialists can determine the speeds at which vibrations rise above normal levels and which machinery components are causing the problems. The machinery speed ramps can then be altered to provide the most vibration-free path to full speed operation.

Benefits of JTFA

• With powerful computing platform, all measurement points on the winder or calender are measured simultaneously. The causes and paths of vibrations can be clearly identified and isolated to certain rolls or components.
• Speed steps can be set to avoid resonant frequencies and provide the smoothest operation in calender or winder without breaks and customer roll quality problems.
• Roll cover lifetimes can be extended by avoiding vibrations and stresses.
• The positioning of calender rolls can be optimized to provide the smoothest operation. Problem positions for certain rolls can be avoided.