Method and device for drawing a web through a group of drying cylinders

Abstract

A method in a drying group or groups provided with a single-wire draw in a multi-cylinder dryer of a paper machine in the draw of a web. The multi-cylinder dryer comprises drying cylinders heated by means of steam or equivalent, with the web being pressed by a drying wire against the cylinder faces of these drying cylinders. The multi-cylinder dryer has leading or lower cylinders on which the web runs outside the drying wire which is, for example, a felt. The leading cylinders or rolls are provided with holes passing through a mantle of the leading cylinders or rolls, these holes being fitted to open into an inner space of negative pressure within the leading cylinder or roll and to open, at an opposite end, into grooves provided on a mantle face of the rolls. The negative pressure inside the roll is arranged to be transmitted to the grooves provided on the outer face of the roll mantle, so that an adhesion force is applied to the web through the grooves. In the method, a negative pressure is applied to the entire inside mantle of the roll, and free flow of air is permitted through the holes from an area above the cylinder and into the interior space within the cylinder. The present invention further concerns a device for use in the single-wire draw of the multi-cylinder dryer of the paper machine, and also to a paper-machine cylinder itself.