Suction roll of a web, or sheet, of paper in a paper converting machine

A suction roll of a web, or sheet, of paper, fed along an advancing direction in a paper converting machine, or similar products, said suction roll comprising:

• a tubular body configured to rotate about a longitudinal rotation axis in a predetermined sense of rotation, said tubular body being provided with an external lateral surface and with an internal lateral surface communicating with each other through a plurality of suction holes organized according to a plurality of longitudinal rows;
• a suction chamber defined within said suction roll and pneumatically connected to a vacuum generation device configured to generate a predetermined vacuum degree;
• a vacuum distribution device configured to selectively put into pneumatic communication said suction chamber with at least one row of suction holes of said plurality, at determined angular positions of said tubular body, and to cause the processed sheet or web of paper to be sucked, and to adhere at a corresponding portion of said external lateral surface of said suction roll arranged between a catching point and a releasing point (P1,P2) having determined angular positions;
• and
• a displacement device configured to move said vacuum distribution device in such a way to change the angular position of said catching point and/or of said releasing point of said web or sheet of paper, and, therefore, to anticipate, or postpone, the catching instant and/or the releasing instant) where said web or sheet of paper adheres to, or leaves said external lateral surface of said suction roll;
• wherein said displacement device is configured to move said vacuum distribution device during said rotation of said tubular body about said longitudinal rotation axis, in such a way to progressively follow the increase or decrease of the advancement speed of the web or sheet of paper.