A suction or blow thermal roller includes: a cylindrical body extending along a longitudinal direction; the cylindrical body including at least one inner tubular element and at least one outer tubular element that is concentrically arranged around the inner tubular element; the inner tubular element includes an outer diameter d and the outer tubular element includes an inner diameter D, being D>d; two hubs, each arranged at one end of the cylindrical body; at least one heat-exchange chamber realized between the inner tubular element and the outer tubular element. The roller includes a coating layer for the inner tubular element. The coating layer includes at least one rib arranged along a helical path around the longitudinal direction. The at least one rib is made in one piece in the coating layer, realizing at least one helical channel between the coating layer and the outer tubular element.

An improved conveying roller for a web or a sheet in a paper converting machine comprises a first cylindrical tubular body having a plurality of radial holes arranged in substantially longitudinal rows, and a second fixed tubular body arranged coxially within the first cylindrical tubular body. The first cylindrical tubular body is capable of rotation relative to the second fixed tubular body. Slidable sealing elements are positioned between the first cylindrical body and the second fixed tubular body to define at least one suction or vacuum chamber. The chamber is suitable for being brought selectively in communication with at least one row of the radial holes during the relative rotation of the bodies.

A roll (1) for folding, or interfolding, a web, or sheet, of paper, (100) fed along an advancing direction in a paper converting machine, or similar machines, comprises a tubular body (10) configured to rotate about a longitudinal rotation axis (101), and having an external lateral surface (11) and an internal lateral surface (12) pneumatically communicating through a plurality of suction holes (3a, 3b) organized in a predetermined number of suction groups (60). Each suction group (60) comprises a predetermined number of close longitudinal rows (30a, 30b) of suction holes (3a, 3b) distributed along the tubular body (10). A suction chamber (20) is, then, provided arranged internally to the roll (1) for folding, or interfolding, and pneumatically connected to a suction device generating a predetermined vacuum level. Each suction group (60) comprises at least 3 close longitudinal rows (30a, 30b, 30c) of suction holes (3a, 3b, 3c) configured to hold each sheet, or web, of paper (100) on the roll (1) at a respective portion of the external lateral surface (11).

A conveying unit includes a rotatable roller having a first through-hole between the inside and the outside of the roller. A cylindrical member inside the roller has an opening and defines an annular chamber between the member and the roller. An insert borne by the roller inserted in the first through-hole thereof and contacting an external surface of the cylindrical member has a second through-hole in communication with the outside of the roller and extending through the first through-hole and the annular chamber. The first through-hole of the opening is configured such that, when the roller rotates, the insert transits at the opening, temporarily placing the outside of the roller in fluid communication with the annular chamber via the second through-hole, so that a sheet outside the roller and at the first through-hole is pulled against the roller by aspirating means and is conveyed.

An interfolding machine (1) is described, including folding rollers (3). Such a roller has a cylindrical sleeve (3C) having a rotation axis (3A), an outer surface (3X) and an inner surface (3Y) defining an inner axial cavity (23) of the cylindrical sleeve (3C). The cylindrical sleeve includes, furthermore, a plurality of suction holes (41, 43) which extend from the outer surface (3X) to the inner surface (3Y) of the cylindrical sleeve (3C). The suction holes are arranged depending on longitudinal alignments (42, 44), parallel to the rotation axis (3A) of the cylindrical sleeve (3C) and angularly staggered in relation to one another. Inside a suction chamber (23A) in the cylindrical sleeve (3C), shutters are stationarily arranged having closing surfaces (37A) cooperating with the inner surface (3Y) of the cylindrical sleeve (3C) to selectively close the suction holes.

Suction roller structure for the pneumatic transport of sheets inside an interfolding unit, comprising a suction source, an external roller (3) rotating with respect to the cylinder (1) and provided with longitudinal rows of bores (4) angularly spaced and selectively communicating with said internal cavity (2) during the angular rotation of the roller (3), a distribution of pneumatic valves (5) that are normally closed, inserted between said internal cavity (2) and at least one bore (4), cam means (6) operatively associated with the rotation of the roller (3) and arranged to open one or more of said valves (5) at one or more angular positions taken by the roller (3).

A conveying unit includes a rotatable roller having a first through-hole between the inside and the outside of the roller. A cylindrical member inside the roller has an opening and defines an annular chamber between the member and the roller. An insert borne by the roller inserted in the first through-hole thereof and contacting an external surface of the cylindrical member has a second through-hole in communication with the outside of the roller and extending through the first through-hole and the annular chamber. The first through-hole of the opening is configured such that, when the roller rotates, the insert transits at the opening, temporarily placing the outside of the roller in fluid communication with the annular chamber via the second through-hole, so that a sheet outside the roller and at the first through-hole is pulled against the roller by aspirating means and is conveyed.

Suction roller structure for the pneumatic transport of sheets inside an interfolding unit, comprising a suction source, an external roller (3) rotating with respect to the cylinder (1) and provided with longitudinal rows of bores (4) angularly spaced and selectively communicating with said internal cavity (2) during the angular rotation of the roller (3), a distribution of pneumatic valves (5) that are normally closed, inserted between said internal cavity (2) and at least one bore (4), cam means (6) operatively associated with the rotation of the roller (3) and arranged to open one or more of said valves (5) at one or more angular positions taken by the roller (3).

A suction or blow thermal roller includes: a cylindrical body extending along a longitudinal direction; the cylindrical body including at least one inner tubular element and at least one outer tubular element that is concentrically arranged around the inner tubular element; the inner tubular element includes an outer diameter d and the outer tubular element includes an inner diameter D, being D>d; two hubs, each arranged at one end of the cylindrical body; at least one heat-exchange chamber realized between the inner tubular element and the outer tubular element. The roller includes a coating layer for the inner tubular element. The coating layer includes at least one rib arranged along a helical path around the longitudinal direction. The at least one rib is made in one piece in the coating layer, realizing at least one helical channel between the coating layer and the outer tubular element.

An interfolding machine (1) is described, including folding rollers (3). Such a roller has a cylindrical sleeve (3C) having a rotation axis (3A), an outer surface (3X) and an inner surface (3Y) defining an inner axial cavity (23) of the cylindrical sleeve (3C). The cylindrical sleeve includes, furthermore, a plurality of suction holes (41, 43) which extend from the outer surface (3X) to the inner surface (3Y) of the cylindrical sleeve (3C). The suction holes are arranged depending on longitudinal alignments (42, 44), parallel to the rotation axis (3A) of the cylindrical sleeve (3C) and angularly staggered in relation to one another. Inside a suction chamber (23A) in the cylindrical sleeve (3C), shutters are stationarily arranged having closing surfaces (37A) cooperating with the inner surface (3Y) of the cylindrical sleeve (3C) to selectively close the suction holes.