fi=214 Kone- ja valmistustekniikka|sv=214 Maskin- och produktionstektik|en=214 Mechanical engineering|https://www.doria.fi:443/handle/10024/920792024-03-28T09:34:17Z2024-03-28T09:34:17ZModelling and control of a forward roll coaterLind, Simonhttps://www.doria.fi:443/handle/10024/1837612022-02-16T12:30:11Z2022-02-16T12:21:50ZModelling and control of a forward roll coater
Lind, Simon
A roll coater applies a coating to a substrate by two or more rotating rolls. The studied case is a 3-roll forward roll coating system. The system's main objective is to apply the base coating to sandpaper. This is done by having the paper rest on a web that travels through the web and application roller. The continuous web lays on the web roller, and the coating is present on the application roller. The distance between the rollers is called the gap and will be one of the main controlling variables in managing that the correct amount of coating is applied to the paper. There are two different kinds of gaps present, one between the web and application roller and one between the metering and application roller. The one between the metering and application roller is controlling that the right amount of coating is applied to the application roller. This gap is usually run with a negative distance, meaning that the rolls are pressed together. The outer layer of the application roller is made out of deformable material to ensure that the rolls do not clash. The system is in a fully flooded regime when the gap between the web and application roller is filled with coating, and a rolling bank is present before the gap. Reducing the amount of coating in the gap will make the bank disappear, and the system will be in a starved configuration. The data for the system is collected by a sensor moving back and forth across the web’s width direction.
A feedback control system is built for the coating system in Simulink. The primary control variables are the gaps between the rolls and the speed of the metering roll. A line approximation is added to represent the geometry of the rollers. An estimator is used to ensure that data is available when the sensor is not present. The model seems to fit well when comparing simulated results to data from the plant.
2022-02-16T12:21:50ZThermal flows and conditions in stone wool melt fiberisationJuup, Roosa-Mariahttps://www.doria.fi:443/handle/10024/1772002020-05-06T07:30:20Z2020-05-05T08:23:20ZThermal flows and conditions in stone wool melt fiberisation
Juup, Roosa-Maria
2020-05-05T08:23:20ZMedium speed and High speed engines in marine hybrid applicationsOscar, Sunngrenhttps://www.doria.fi:443/handle/10024/1646632018-11-27T11:00:14Z2018-11-27T09:34:02ZMedium speed and High speed engines in marine hybrid applications
Oscar, Sunngren
2018-11-27T09:34:02ZExperimental comparison of slalom conceptsPirttikangas, Ellahttps://www.doria.fi:443/handle/10024/1641442018-11-16T11:30:20Z2018-11-16T07:44:44ZExperimental comparison of slalom concepts
Pirttikangas, Ella
Studies on paper and board machine runnability began in the late 20th century and most of the studies focused on machine speed increase. Today, the most high-speed paper machines have a single-run construction and machine speeds can reach speeds over 2000 m/min. Runnability equipment is developed to enable the high velocities and the objective is to diminish the negative effects associated with the machine speed increase. Currently, studies focus on energy and cost efficiency, where finding the optimum solution for the certain framework is required.
The objective of the thesis was to study the forces and the phenomena at a single-run paper or board machine, which causes harmful effects on the web. In the thesis, a selection of runnability concepts are compared at different machine speeds and the comparison analyses their functionality, energy consumption and cost. The concepts were tested at pilot scale in the Technology Centre of Valmet in Raisio.
The comparison of the functionality focused on how the different concepts stabilised the web at the closing nip and over the rotation of the bottom cylinder. The comparison concluded that the existence of a surface pattern was beneficial both for the closing nip over pressures as well as the support over the rotation. Furthermore, having a stabiliser nozzle targeting the closing nip was useful especially at low machine speeds and the suction roll concepts were found to be over dimensioned at machine speeds below 1400 m/min.
The energy consumption and cost evaluation, combined with the functionality analysis suggests that the concepts using a suction roll are the most fitting for higher velocities, as the functionality of the concepts with the passive bottom rolls decrease or the operational cost become higher compared to the suction roll concepts.
2018-11-16T07:44:44Z