Gerd Michaelis

Tension control: dancer rolls or load cells

Two different ways of regulating the paper web tension in an off-machine coater, by using either a tension controller with load cells, or a position controller using dancer rolls, are compared. The two systems are analyzed from the regulation point of view: system stability and response times. The stability and response analysis was performed on a computer model using data from an offline coating machine. The machine is equipped with both systems and can be run with either tension or position control. Practical results based on measurements made on-site included.<<ETX>>

Direct drives and attached motors

Requirements from customers and machine manufacturers due to installation, energy and maintenance costs, space limitations and the permanent struggle to minimize the number of components have led to new drive solutions. Gearless drives and especially attached drives offer also further advantages in operation, exhibiting stiffer drive trains and allowing better drive control. Gearless and attached motor solutions are well proven in other branches of industry, even though mostly at much lower powers. The challenge of up-scaling these motors and adapting them to the (in some places) hostile environment of a paper machine was successfully mastered. Additionally, options for retrofitting existing machines are given.