Smartroll
1. Background
Rolling contact units represent very typical finishing systems in paper industry. A standard arrangement is to press two polymer-covered metallic rolls in contact for transferring and penetrating a pasta coating into the surface of the paper web. Although the unit process is relatively simple and the system itself represents quite robust design, complex contact dynamical problems arise in almost every unit for higher running speeds. These problems appear in form of limit-cycle oscillations, whose amplitude experiences resonance amplification at rotation frequencies, which are integer fractions of the eigenfrequency of the roll system in contact oscillations. This phenomenon relates to the recovery dynamics of the polymeric roll cover material. An intensive research activity has been addressed to solve this problem since 1998 by means of the following applied research projects:
NIPDYN project, 1998-2000
POLYROLL project, 2001-2003
ACTIVEROLL project, 2003-2005
Figure 1: Smartroll installation
Figure 2: Smartroll cylinder measurement sensors installation
In NIPDYN project the build-up of a pilot roll plant was carried out in cooperation with industrial companies. The system provides a platform to roll contact research in conditions similar to the ones in industrial units. A significant and unique property, however, is the possibility for free modification of the system configuration by means of adjustable system and running parameters. The design for configurability and dimensional analysis of the roll system produced one dissertation (Kivinen). Another dissertation (Yuan) considered the model and stability analysis of delay vibrations in polymer covered rolls.
In POLYROLL project the pilot system was completed with a wireless link in order to transmit the measurement data from the rolls to nonrotating reference. The data reveived from the accelerometers was utilized in modal analysis of rotating rolls, which task is almost impossible with sensors fixed to the nonrotating reference. The results of this development were reported in a dissertation (Järvinen). Another research line produced mathematical models, which link together strains, strain rates and stresses for roll cover polymers at different temperatures. The results can be found also in one dissertation (Vuoristo).
In ACTIVEROLL project the focus was in measurements and control of rolling contact using alternatively internal roll strains or sensing the capacitance changes of the roll cover material. Internal measurements and the corresponding inverse problem solution form one dissertation (Romppanen). Furthermore, a fuzzy logic based algorithm has been developed to eliminate the delay resonance by means of controlling the time delay, which is a dissertation subject as well (Salmenperä). Initialised by one industrial partner company, an external self-tuning dynamic mass damper has been installed to the system in order to damp the delay-resonance.
The purpose of the SMARTROLL project is to investigate the roll responses under direct drives and to install fast piezoceramic actuators and sensors for producing and measuring a dynamically stable line contact.
2. Goal
The purpose is to develop actuator and sensor solutions for realizing fast and stable rolling contact. The development work and the whole project is divided to the following sub-projects:
I Direct roll drive
II Active vibration damping of rolls
III Line load sensing by piezoelements
The solutions introduced improve the performance of the roll unit in terms of higher speed and accurate line load control. Better performance is obtained by less complex drive solution and broad frequency band of piezoceramic transducers.
3. Timetable
1.9.2005…31.8.2007
Responsible project head:
Erno Keskinen, erno.keskinen@tut.fi
Executive project head:
Juha Miettinen, juha.s.miettinen@tut.fi