Suction roller arrangement for transporting web-form material

A device for transmitting motion to a strip of material by looping a strip of material over a rotating member in a region to which suction pressure is applied, having in combination

• a cylindrically shaped hollow roller body, for rotating about an axis extending longitudinally through said body,
• having a porous sintered metal wall with an interior surface defining a chamber and pores extending radially through said wall from an outer surface to said interior surface and chamber,
• said pores through said wall provide zones of varying porosity positioned with respect to each other axially of the roller body,
• said zones consisting of a zone of greater permeability positioned in said body adjacent a zone of lesser permeability, wherein said zone of greater permeability has pores ranging in diameter from 35-70 um and the zone of lesser permeability has pores of a diameter of 30 um or less,
• a hollow stator positioned within the chamber of the roller body and having an inner chamber and a plurality of external surfaces on said stator formed to provide at each external surface a spacing from the interior surface of the roller body, said stator having in zones at said external surfaces apertures extending to the inner chamber and said stator having at least one zone absent of apertures at an axial end of the stator,
• means at aid aperture-containing zones for providing a suction force at said apertures upon rotation of the roller body,
• so constructed and arranged that the zone with the apertures is positioned radially within the zone of greater permeability.