Roll in a paper or board machine and a dryer group in a paper or board machine

摘要

A roll in a paper or board machine has a roll frame or center shaft (15) with bearings mounted at its ends and a groove-like surface structure (10). There is a contact between the surface structure and the center shaft so that an essentially closed structure is formed. The roll produces a vacuum that keeps the web attached to the outer surface of a fabric in the fabric wrap area of the roll circle by utilizing the boundary layer airflows of the surface structure flow and/or of the web. A dryer group has at least one contact dryer cylinder and at least one turning roll with a single fabric run arrangement.