On the Closed Loop Control Systems for Web Offset Presses.

Several projects on the development of closed loop control have been made and are continued in GTL. The first group of variables to be controlled in web offset is the inking. The problems of measuring and controlling are analyzed in particular those connected with four-color heat-set type of operation. The previous work done by the same group for development of on-press multichannel density monitoring systems is reported to continue in two directions. First to use transportable models in process identification (for control purposes) and testing of presses and their presetting systems. Second to develop final sensors for process control systems. The process analysis has to be completed as well. The role of water feed and transfer through inker, plate and blanket can be studied both theoretically using simulation and experimentally using sensors or tracer methods. The closed loop control system may be expandable to include further variable groups such as water feed, ink or water temperatures. It is expected that advanced demonstrations of closed loop control systems for inking are carried out during this year. There are, however, many open questions and the system know-how required is much deeper than evaluation earlier. The process analysis has to be completed as well. The role of water feed and transfer through inker, plate and blanket can be studied both theoretically using simulation and experimentally using sensors or tracer methods. The closed loop control system may be expandable to include further variable groups such as water feed, ink or water temperatures. It is expected that advanced demonstrations of closed loop control systems for inking are carried out during this year. There are, however, many open questions and the system know-how required is much deeper than evaluation earlier.