Abstract: A unit (1) for processing a web (2) of packaging material, and having at least a first station (3) for forming a number of through holes (4) in the web (2); a second station (6) for sealing the holes by applying respective opening devices (7, 8); a feed device (10) for step feeding the web (2) along a path (P) through the first and second station (3, 6); a position sensor (21) generating a presence signal (S) indicating the passage, past the sensor (21), of reference elements (C; 4) carried by the web (2) and bearing a predetermined relationship with the holes (4); a control device (20) for controlling the feed device (10) in response to the presence signal (S); and actuating means (22) cooperating with the second station (6) to move the second station in a direction parallel to said path (P), and activated by the control device (20) to adjust the position of the second station (6) as a function of the presence signal (S).

Abstract: A unit (1) for processing a web (2) of packaging material, and having at least a first station (3) for forming a number of through holes (4) in the web (2); a second station (6) for sealing the holes by applying respective opening devices (7, 8); a feed device (10) for step feeding the web (2) along a path (P) through the first and second station (3, 6); a position sensor (21) generating a presence signal (S) indicating the passage, past the sensor (21), of reference elements (C; 4) carried by the web (2) and bearing a predetermined relationship with the holes (4); a control device (20) for controlling the feed device (10) in response to the presence signal (S); and actuating means (22) cooperating with the second station (6) to move the second station in a direction parallel to said path (P), and activated by the control device (20) to adjust the position of the second station (6) as a function of the presence signal (S).