| 摘要 |
A unit (1) for carrying out a first operation and a second operation onto a first area (2d, 2e, 2f) and a second area (2a, 2b, 2c) of a packaging material; said first area and said second area being spaced for a first distance (e) along direction (A) when a portion (20) of packaging material comprising said first area and said second area is flat; unit (1) comprising: a feeding group (6) for feeding a web (3) of packaging material along said direction (A) and in a first sense; a first tool (28a, 28b, 28c) adapted to carry out first operation on said first area arranged in a first desired position; a second tool (27a, 27b, 27c) adapted to carry out second operation on said second area arranged in a second desired position; said first and said second tool being spaced for a second distance (d) along said direction (A); said feeding group (6) comprising advancing means (10, 16) controllable to arrest web (3) in a position, at which said second area is spaced for an intentional offset (X) from second desired position; and actuating means (50) controllable for moving said second area towards second desired position, so as to recover offset (X); the absolute value of the difference between first distance (e) and second distance (d) being equal to offset (X). |
