Analysis of chatter marks damage on the Yankee dryer surface of a tissue machine

A tissue machine suffering from Yankee chatter marks has been experimentally investigated. A series of vibration measurements during normal operation at various Yankee speeds on both the creping and the cleaning blade holders have been carried out. The analysis in a frequency range up to 20 kHz has permitted to identify speed dependent frequency peaks and broadband high frequency vibration content on the creping zone. Hence, an experimental modal analysis of the creping blade and holder has been carried out with the machine stopped to identify its natural frequencies. As a result, resonance conditions have been identified due to the gearbox excitation originated by the meshing process. The study of the corresponding mode shapes has permitted to understand the vibration behavior and its relationship with the damage. To solve the problem, the creping blade holder structure has been redesigned to detune the resonances. Since this overhaul, comparable measurements have confirmed a significant reduction of vibrations and high frequency noise. The appearance of chatter marks has been minimized.

► Vibrations were measured on the creping area of a machine with chatter marks.
► Speed dependent frequencies with high amplitudes were detected.
► Resonance responses on creping holder excited by gear mesh process were identified.
► A correlation was found between mode shapes and vibrations up to 20 kHz.
► A detuning by structural modification of the creping holder was accomplished.