Unit for the glue application of at least two labels to containers

A unit for the glue application of labels to containers, comprising:

• a supporting structure (7);
• at least one first application device (8) rotatably mounted on the supporting structure (7) so that it rotates about a main axis of rotation (Z) and therefore cyclically passes between a first label pickup position (25) and a first position (26) for application of the label to a container (2);
• the first application device (8) comprising at least a first applying surface (10) for pressing a label on a container (2);
• and the first application device (8) moving along a first trajectory which, at least at the first application position (26), is circular and centred on the main axis of rotation (Z);
• first rotation means for moving the first application device (8) along the first trajectory with a first rotational speed relative to the main axis of rotation (Z);
• at least one second application device (9) rotatably mounted on the supporting structure (7) so that it rotates about the main axis of rotation (Z), moving along a second trajectory (11) and therefore cyclically passing between a second label pickup position (23) and a second label application position (24);
• the second application device (9) comprising at least a second applying surface (12) for pressing a label on a container (2);
• second rotation means (15) for moving the second application device (9) along the second trajectory (11) with a second rotational speed relative to the main axis of rotation (Z);
• the first application device (8) and the second application device (9) being positioned at two separate and superposed portions of the main axis of rotation (Z), each for applying at least one label on a separate portion of the same container (2);
• in practice, at least at the second application position (24) the second applying surface (12) being at a distance from the main axis of rotation (Z) which is respectively less than or greater than the distance between the main axis of rotation (Z) and the first applying surface (10) located in its first application position (26);
• and
• the second application device (9) also pivoting about an axis of oscillation (O) rotating about the main axis of rotation (Z) with the second rotational speed;
• the unit being characterised in that the second rotational speed is identical to the first rotational speed;
• also being characterised in that it also comprises a first guide element (29) and in that the second application device (9) comprises two first follower elements (30) which are slidably connected to the first guide element (29) for following its course during rotation of the second application device (9) about the main axis of rotation (Z), the interaction between the first follower elements (30) and the first guide element (29) producing the second trajectory (11) for movement of the second application device (9);
• and also being characterised in that, at least at a stretch of the second trajectory (11) for movement which causes the transit of the second application device (9) close to and at the second application position (24), the interaction between the first follower elements (30) and the first guide element (29) causes a rotation of the second application device (9) about the axis of oscillation (O) in such a way that the second applying surface (12) rotates respectively in the same direction or in the opposite direction to the direction of rotation of the device about the main axis of rotation (Z), respectively if, in practice, at the second application position (24) the second applying surface (12) is at a distance from the main axis of rotation (Z) which is less than or greater than the distance between the main axis of rotation (Z) and the first applying surface (10) located in its first application position (26).