Machine for wrapping groups of products with tubular lengths of stretch film

1. A machine for wrapping groups of products ( 7 ) with lengths of tubular stretch film ( 4 ), comprising:

a rotating carousel ( 1 ) equipped with a plurality of wrapping units ( 2 ) having bars ( 3 ) for stretching to size a succession of tubular film lengths ( 4 );

said carousel rotating each wrappping unit to a plurality of stations including:

a receiving station (S 1 ) where the wrapping unit receives the film lengths;

a placing station (S 3 ) where the wrapping unit places the stretched lengths of tubular film ( 4 ) around respective groups of products ( 7 ) to be wrapped, wherein the groups of products are fed one after the other to the placing station (S 3 );

an unloading station (S 4 ) where the wrapping unit unloads the wrapped groups of products ( 8 ) from the carousel ( 1 );and

a dedicated stretching station (S 2 ) where the wrapping unit stretches the film lengths ( 4 ), and wherein the bars ( 3 ) at least completing the stretching of the film lengths ( 4 ) at said dedicated stretching station (S 2 ).

2. The machine according to claim 1 , wherein the dedicated station (S 2 ) is equipped with actuators ( 15 ) that drive the bars ( 3 ) until the film lengths ( 4 ) have been fully stretched to size, the actuators ( 15 ) being fixed relative to the rotating carousel ( 1 ).

3. The machine according to claim 1 , further comprising first and second actuators ( 15 , 32 ) for driving the bars ( 3 ) independently in the vertical and horizontal directions.

4. The machine according to claim 3 , wherein the vertical actuators ( 15 ) for driving the bars vertically are positioned in such a way as to drive the bars ( 3 ) symmetrically about a horizontal plane ( 14 ′).

5. The machine according to claim 4 , wherein the horizontal plane ( 14 ′) coincides with a table ( 14 ) for loading/unloading the groups of products ( 7 ).

6. The machine according to claim 3 , wherein the actuators ( 32 ) for driving the bars ( 3 ) horizontally are mounted on wrapping units ( 2 ).

7. The machine according to claim 3 , further comprising encoder devices for controlling the actuators ( 32 , 15 ).

8. The machine according to claim 3 , wherein each wrapping unit ( 2 ) comprises four independent horizontal actuators ( 32 ) acting on four mobile carriages ( 11 ) arranged in pairs running on horizontal guides ( 25 ) made on two vertically mobile carriages ( 20 ), each carriage ( 11 ) being equipped with a stretch bar ( 3 ).

9. The machine according to claim 8 , further comprising means for detecting the position and movements of each mobile carriage ( 11 ) in such a way as to detect the reciprocal position of each pair of bars ( 3 ) mounted on the respective carriage ( 20 ).

10. The machine according to claim 1 , wherein the carousel ( 1 ) comprises a set of guides ( 13 ) comprising one or more sections (T 1 –T 4 ) positioned around at least part of the circumference of the carousel ( 1 ) for guiding the movement of the bars ( 3 ) as the carousel ( 1 ) rotates.

11. The machine according to claim 10 , wherein each of the mobile carriages includes a pin, and wherein, at the dedicated stretching station (S 2 ), the set of guides ( 13 ) comprises one or more vertically mobile sectors ( 57 ) for receiving the pins ( 21 ) on the carriages ( 20 ) and which are driven by vertical actuators ( 15 ) in such a way as to move the bars ( 3 ) vertically and thereby stretching the length of film ( 4 ).

12. The machine according to claim 10 , wherein each of the mobile carriages includes a pin, and wherein the set of guides ( 13 ) comprises at least one section (T 3 ) comprising one or more cam profiles ( 59 ) for receiving the pins ( 21 ) on the carriages ( 20 ) in order to guide the vertical movement of the bars ( 3 ) according to one or more predetermined paths.

13. The machine according to claim 12 , wherein the cam section (T 3 ) is arranged in a such a way as to move the bars ( 3 ) towards each other and thereby guiding the film length ( 4 ) as it shrinks on the group of products ( 7 ) to be wrapped.

14. The machine according to claim 10 , wherein the set of guides ( 13 ) comprises at least one section (T 4 ) comprising sectors ( 57 ) that are driven vertically by motors ( 50 ).

15. The machine according to claim 10 , wherein the guides ( 13 ) are designed to actively drive the bars ( 3 ) and exert a stretching force on the film length ( 4 ) as the carousel ( 1 ) rotates.

16. The machine according to claim 1 , wherein each of the bars ( 3 ) comprise an idle roller.

17. The machine according to claim 16 , wherein each of the idle rollers is covered with non-stick material.

18. The machine according to claim 1 , wherein each of the bars ( 3 ) comprises a power-driven roller ( 56 ).

19. The machine according to claim 1 , wherein the dedicated stretching station (S 2 ) comprises suction cups acting on the film in such a way as to temporarily hold the film as it starts being stretched, thus avoiding undesired movements of the film and uneven stretching of the film length ( 4 ).

20. The machine according to claim 1 , further comprising pusher means ( 22 ) for feeding groups of products ( 7 ) to the placing station (S 3 ) and pusher and/or extractor means for unloading the packages ( 8 ) from the carousel ( 1 ).

21. The machine according to claim 1 , further comprising stabilizing plates ( 23 ) acting on the tops of the groups of products ( 7 ) while they are being placed in a film length ( 4 ) and/or on the wrapped groups of products ( 8 ) while they are being transferred from the placing station (S 3 ) to the unloading station (S 4 ).

22. The machine according to claim 1 , wherein the groups of products are fed one after the other to the placing station (S 3 ) by a product loading table ( 14 ) that moves to and fro between a retracted position and an advanced position corresponding to the loading position.

23. The machine according to claim 22 , wherein the to and fro movement of the table ( 14 ) is achieved by a fixed flat cam ( 57 ′) which is located on a supporting surface ( 58 ′) and which engages with a pin ( 59 ′) on the underside of the table ( 14 ) so that the table follows the fixed flat cam profile as the carousel ( 1 ) rotates.

24. An installation for wrapping groups of products in tubular lengths of stretch film ( 4 ) comprising a first and a second machine for wrapping groups of products ( 7 ) with lengths of tubular stretch film ( 4 ) according to claim 1 , wherein the carousels are connected by a conveyor belt ( 26 ) that feeds the carousel ( 1 ′) of the second machine with a succession of groups of wrapping products ( 8 ) unloaded from the first carousel ( 1 ) of the first machine, the groups of wrapped products ( 8 ) being transferred by the conveyor ( 26 ) to the placing station (S 3 ′) of the second carousel ( 1 ′) in a position that is turned about a vertical axis by 90° relative to the position in which the groups of the products were fed to the placing station (S 3 ) of the first carousel ( 1 ), so that groups of products ( 7 ) are wrapped in two tubular film lengths ( 4 , 4 ′) in crossed fashion.

25. The installation according to claim 24 , wherein the placing station (S 3 ′) of the second carousel ( 1 ′) comprises a unit ( 28 ) for making a handle comprising a portion of a film length ( 4 ′).

26. The installation according to claim 25 , wherein the handle making unit ( 28 ) is equipped with a gripper ( 29 ) that grips the top ( 30 ) of the film length ( 4 ′) and gathers the top of the film length up like a strap forming a handle by which the pack can be carried.