Abstract: A folding, or interfolding, unit, (100) for folding, or interfolding, a first and a second plurality of sheets of paper (105a, 105b) in a machine for converting paper, comprises a first and a second folding, or interfolding, counter-rotating rolls (1a, 1b) configured to rotate about a respective longitudinal rotational axis (110a, 110b) and providing a plurality of suction holes (11a, 11b, 12a, 12b). A vacuum generation device and a vacuum distribution device (40a, 40b) are, furthermore, provided for selectively putting into pneumatic communication the vacuum generation device with at least a row of the aforementioned suction holes (11a, 11b, 12a, 12b).

Abstract: 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.

Abstract: A method and a machine for rewinding a web (1) for making a log (2a), in particular for the production of rolls of toilet paper, rolls of all purpose wipers or household non woven fabric, industrial rolls and the like. The rewinding is carried out according to the steps of feeding a web (1) of paper into a winding cradle (4); arranging upstream of the cradle (4) a counter support roller (8) comprising at least a cutting slit (9) transversal to the web and a cutting roller (11) with a blade (10) so that it is possible the cut or tear the web (1) for contact of the blade (10) with the web (1); concluding the winding of the log (2a); winding the new log (2b) up to a predetermined length of the web (1); rotating with sliding the counter support roller (8) on the web (1) during the winding of the new log (2b) for causing the blade (10) to cut the web in a desired chosen location.

Abstract: A machine (1) for interfolding sheet material (4a, 4b) starting from a web (3a, 3b) of paper and the like. A sequence of offset sheets (4a, 4b) is formed on folding rollers (7a, 7b) which are counter-rotating with respect to each other and have a plurality of circumferential grooves (15a, 15b), in which oscillating folding arms engage (20a, 20b) so as to form a stack (17) of interfolded sheets (4a, 4b). The folding arms (20a, 20b) have pivots (21) very close to the periphery of the folding rollers (7a, 7b), inside or outside of the grooves (15a, 15b). Moreover they can be operated by a crank mechanism that allows to the grooves (15a, 15b) to be shallow enough also in case of rollers (7a, 7b) of enlarged diameter. For the same reason, the folding arms (20a, 20b) can have a bent portion.

Abstract: A method and a machine for the production of interfolded stacks (17) formed by a plurality of sheets (4a,4b) comprising the steps of: transversally cutting or tearing sheets obtained from at least one web (3a,3b) and offset with respect to one another so that a sequence of offset sheets is created; passage of the sheets on folding rollers (7a,7b) which comprise sucking means for the alternate holding of the sheets (4a,4b) in order to obtain an interfolded disposition; formation of a continuous interfolded stack downstream of the folding rollers. Upstream of the folding a step of treatment of the sheets is provided in order to make them, at least in certain zones (14), enough permeable to air, in particular through perforating means. These perforating means can be provided on rollers (10a,10b) having sharpened points (11a,11b).