Device for changing web tension in rotary printing machine

摘要

The tension is set by rollers whereby the roller (1) of constant circumference is driven at constant speed in dependence on the machine speed and is in direct contact with a contact pressure roller (3) which is coated with a rubber-elastic substance. The web (8) is looped round the contact pressure roller under tension and is moved by this roller slip-free. The contact pressure force of the contact pressure roller on the driven roller (1) and thus the circumferential speed of the contact pressure roller are variable. The diameter of the contact pressure roller is greater than that of the roller and the loop angle of the web is greater than or equal to 180 degs.