Analysis and elimination of the cause of vibrations in paper rolling machinesCopyright: © IGMR
Two-drum winders are used for cutting and winding a wide variety of papers. A web tension is created between unwinding and support rollers in the paper web to guide the paper web through the cutting section without defects and creases, where the paper web is cut lengthwise. In order to counteract the formation of wrinkles before the cutting section, the paper web is stretched crosswise to the paper running direction and then rolled up continuously on individual cores.
When operating at high processing speeds, especially when processing solid papers with high coefficients of friction, strong paper roll vibrations occur again and again, which in extreme cases can lead to the levering out of individual rolls. Although paper roll vibrations are currently controlled to such an extent that roll ejection can be prevented, the cause of vibration and the mechanism of origin were still largely unknown. Numerous influences must be taken into account when investigating the dynamic behaviour of the machine. These include
- Operating parameters such as web tension or web speed
- Product properties such as friction behaviour, geometric errors or penetration stiffness, and
- Constructive parameters such as machine geometry or the type of web guidance
Since the complex interaction of all influencing variables cannot be fully captured by tests and measurements, a multibody model of the double drum winder was developed by the Institute of Transmission Technology and Machine Dynamics. The model includes numerous model elements and model parameters to reproduce a wide variety of physical effects. These effects include, for example
- geometric errors of the paper roll
- the mutual penetration of the support rolls and the paper roll and the associated generation of frictional forces and slip in the contact zones, and
- the translational and rotational spring and damping characteristics of the roll bodies and bearings.