Folding or interfolding unit for folding or interfolding sheets of paper

Abstract

A folding or interfolding unit includes first and second folding or interfolding rolls to fold or interfold the sheets of paper according to a predetermined folding or interfolding configuration. The first and second folding or interfolding rolls include, respectively, a tubular body configured to rotate in a predetermined direction of rotation about a longitudinal rotation axis, and gripping groups, each of which includes a mechanical gripping member configured to move, at a gripping point, from an opening position to a closing position, which is arranged to mechanically hold the sheets up to a releasing point. Each gripping group includes at least one suction hole associated to each mechanical gripping member. A vacuum distribution device selectively pneumatically connects at least one suction hole at a time to a device for generating a predetermined vacuum degree, to cause the sheets of paper to adhere between starting and ending positions.