| 摘要 |
An apparatus (1) for wrapping products with plastic film (50) comprises: a ring-shaped element (3) supporting a carriage (4) that moves around the ring - shaped element (3); drive means (5) for moving the ring-shaped element (3) relative to the group (P) of products to be wrapped; main motor means (6) associated to the ring-shaped element (3) and designed to drive the carriage (4). The carriage (4) mounts a roll (7) of plastic film and a pre-stretching unit (8) driven by suitable drive means (9). The pre-stretching unit (8) comprises a pair of rollers (10) for pre-stretching the film and a transmission and control roller (12) that swings towards and away from the group (P) of products and is designed to start or stop film feed according t o its position relative to the group (P) of products to be wrapped. The drive means (9) comprise a kinematic chain consisting of the main motor means (6) and a ring-shaped, continuous drive take-off track (13) for the pre-stretchi ng unit (8) drive means (9) which comprise an engage/release unit (14) connecte d to and controlled by the transmission roller (12) and designed to transmit drive from the ring-shaped track (13) to the pair of pre-stretching rollers (10) according to the position of the transmission roller (12).
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