| 摘要 |
Apparatus for causing paper webs to tear off within rewinding machines, the said web (2) being provided, at regular intervals, with transverse perforation lines which subdivide the web into sheets joined to each other but able to be separated in correspondence of said perforation lines, the apparatus comprising means to cause the tearing of the web (2) upon the passage of a perforation line (p) which separates the last sheet of a log (RO) in the course of formation from the first sheet of the next log to be formed, wherein said tearing means are of pneumatic type (SP) able to direct a jet of compressed air toward the said line (p).Said pneumatic means (SP) comprise a set of nozzles (7) associated, via corresponding solenoid valves (70), with a reservoir of compressed air (71). Said nozzles (7), with the respective solenoid valves and reservoir (71) are positioned externally to a web (2)-feeding roller (RA) whose outer surface is provided with a plurality of circumferential grooves (76) in correspondence of which the nozzles (7) are positioned. |
