Patent ID: 6986831
Filing Date: 2006-01-17
Classification: D21F

Abstract:
1. A suction roll of a paper machine comprising: a perforated shell having an inner surface and an outer surface, and portions of the shell which define a plurality of through holes extending through the shell between the inner surface and the outer surface, each through hole having a second center; and a static suction box sealed against the inner surface of the shell to create a suction zone on the outer surface of the suction roll while the shell rotates, wherein the holes of the shell are situated at distances of varying magnitude from one another such that the hole pattern formed on the inner surface of the shell is irregular, wherein an axial direction is defined which is parallel to an axis of the roll, and wherein a circumferential direction is defined which is perpendicular to the axial direction and extending along the surface of the roll, and wherein a curved line is defined which extends along the surface of the roll having an angle greater than zero with respect to the circumferential direction, and wherein a plurality of first centers of first circles of a diameter greater than the through hole diameter are defined extending in a spiral pattern wrapping around the roll, each of said first centers being positioned on said curved line, and wherein the spacing between the first centers along said curved line is equal, and wherein each of said plurality of through holes has a second center, the second centers being positioned within one of the first circles, the distances between successive through holes measured along said curved line being of varying magnitude and the first circles are of uniform diameter.