Apparatus for wrapping groups of products

1. An apparatus for wrapping groups of products with film, the apparatus comprising:

a first surface;

a second surface;

wrapping means for wrapping groups of products with a length of film, the wrapping means comprising a first electric drive axis;

a film feed unit for defining a length of film according to dimensions of the group of products to be wrapped, the film feed unit comprising a second electric drive axis for moving a defined quantity of film in the direction of the second surface;

a pre-unwinding unit for pre-unwinding film, said pre-unwinding unit comprising a third electric drive axis to move film from an associated roll of film toward the feed unit;

a synchronizing unit that controls the second and third electric drive axes and that is operative between the second and third electric drive axes to synchronize film feed from the pre-unwinding unit;

a plurality of idle film tensioning rollers defining a film path and located between the film feed unit and the pre-unwinding unit, a first group of at least two of the idle tensioning rollers being fixed in position relative to the third electric drive axis and a second group of at least two of the idle tensioning rollers being mounted on a pivoting rocker arm.

2. An apparatus for wrapping groups ( 1 ) of products ( 2 ) with film, the apparatus ( 4 ) comprising at least the following:

a first surface ( 5 ) and a second surface ( 6 ), the first surface ( 5 ) moving in a direction (A) for conveying the products ( 2 ) to the second surface ( 6 ) and forming the product groups ( 1 );

wrapping means for wrapping the groups ( 1 ) with a length of the film ( 3 ), the wrapping means ( 7 ) having a first drive axis (AEl);

a film ( 3 ) feed unit ( 8 ) defining the length of film ( 3 ) whose length depends on the dimensions of the group ( 1 ) of products to be wrapped, the unit ( 8 ) being located below and adjacent to a slot ( 9 ) separating the first surface ( 5 ) from the second surface ( 6 ), the feed unit having a second electric drive axis (AE 2 ) which enables a defined quantity of film ( 3 ) to be unwound in the direction of the second surface ( 6 );

a pre-unwinding unit ( 10 ) for pre-unwinding the film ( 3 ), comprising at least one roll ( 11 ) of film ( 3 ) located upstream of the feed unit ( 8 ) with respect to an unwinding direction (B) and under the first and second surfaces ( 5 , 6 );

a third electric drive axis (AE 3 ) located and operative on the pre-unwinding unit ( 10 ) to move the film ( 3 ) towards the feed unit ( 8 ) according to the film ( 3 ) requirement or feed speed controlled by the second electric axis (AE 2 ) of the feed unit ( 8 );

a unit ( 12 ) which controls the second and third electric axes (AE 2 , AE 3 ) and which is located and operative between the two electric axes (AE 2 , AE 3 ) to synchronize the control of film ( 3 ) feed;

the apparatus ( 4 ) further comprising a plurality of idle film tensioning rollers ( 30 ) located between the roll ( 11 ) and a pair of film feed rollers ( 15 , 16 ), a first group of the idle tensioning rollers ( 30 ) being fixed on a plate ( 31 ) that mounts a third drive ( 14 ), and a second group of the idle tensioning rollers ( 30 ) being mounted on a rocker arm ( 32 ) pivoted on a frame ( 33 ) forming part of the apparatus ( 4 ).

3. The apparatus according to claim 2 , wherein the third electric axis (AE 3 ) is located between the roll ( 11 ) and a roller ( 13 ) that controls the unwinding of the film ( 3 ).

4. The apparatus according to claim 3 , wherein the third electric axis (AE 3 ) comprises at least the third drive ( 14 ) positioned between the roll ( 11 ) and the roller ( 13 ), and the pair of film ( 3 ) feed rollers ( 15 , 16 ), one of which is kinematically connected to the third drive ( 14 ).

5. The apparatus according to claim 2 , wherein the third electric axis (AE 3 ) is located and operative on the film roll ( 11 ).

6. The apparatus according to claim 5 , wherein the third electric axis (AE 3 ) comprises the third drive ( 14 ) axially connected to a rotary drum ( 21 ) that supports the roll ( 11 ) to enable pre-unwinding speed to be directly correlated to the feed and cutting speed of the feed and cuffing unit ( 8 ).

7. The apparatus according to claim 2 , wherein the third electric axis (AE 3 ) comprises at least the third drive ( 14 ) positioned between the roll ( 11 ) and the roller ( 13 ), and the pair of film ( 3 ) feed rollers ( 15 , 16 ), one of which is kinematically connected to the third drive ( 14 ).

8. The apparatus according to claim 7 , wherein the roller ( 15 ) and the third drive ( 14 ) are kinematically connected by a toothed belt ( 17 ) trained around respective wheels ( 18 , 19 ) keyed, respectively, to the roller ( 15 ) and to a shaft ( 20 ) protruding from the third drive ( 14 ).

9. The apparatus according to claim 7 , wherein the third drive ( 14 ) is a variable phase drive.

10. The apparatus according to claim 2 , wherein the third electric axis (AE 3 ) comprises the third drive ( 14 ) axially connected to a rotary drum ( 21 ) that supports the roll ( 11 ) to enable pre-unwinding speed to be directly correlated to the feed and cutting speed of the feed and cutting unit ( 8 ).

11. The apparatus according to claim 2 , wherein the pre-unwinding unit ( 10 ) further comprises means ( 22 ) for controlling the unwound film ( 3 ) wherein said means for controlling the unwound film is positioned between the third electric axis (AE 3 ) and the feed and cutting unit ( 8 ) and connected directly to the control unit ( 12 ).

12. The apparatus according to claim 11 , wherein the control means ( 22 ) comprise:

a tubular roller ( 13 ) guided on both sides by respective vertical guides ( 23 ) and resting freely on the film ( 3 ) being unwound and sliding freely up and down together with the film ( 3 ); and at least

one sensor ( 24 ) for detecting the presence of the roller ( 13 ) and positioned at a point close to a floor (P); the sensor ( 24 ) being connected to the control unit ( 12 ) to send to the control unit ( 12 ) a signal (S) for stopping the second and the third electric axes (AE 2 , AE 3 ) when:

the roller ( 13 ) is at a lowered first position with the film close to the floor (P), wherein the roller ( 13 ) is in a position away from the third electric axis (AE 3 ), for a length of time greater than a preset time, corresponding to absence of a call for film ( 3 ) by the second electic axis (AE 2 ), and

the roller ( 13 ) and the film ( 3 ) are at a raised second position, close to the third electric axis (AE 3 ), for a length of time greater than a preset time, corresponding to absence of film ( 3 ) feed by the third electric axis (AE 3 ).

13. The apparatus according to claim 2 , wherein the first drive axis (AE 1 ) is of the electric type.

14. The apparatus according to claim 13 , wherein the first and second power drive axes (AE 1 , AE 2 ) comprise, respectively, a first variable phase drive ( 26 ) and a second variable phase drive ( 25 ).

15. The apparatus according to claim 2 , wherein the first and second power driven axes (AE 1 , AE 2 ) comprise, respectively, a first variable phase drive ( 26 ) and a second variable phase drive ( 25 ).

16. The apparatus according to claim 15 , wherein the control unit ( 12 ) is connected to the first (AE 1 ), second (AE 2 ) and third (AE 3 ) electric axes to coordinate the respective profiles of motion substantially constituting electric cams.

17. The apparatus according to claim 2 , wherein the control unit ( 12 ) is connected to the first (AE 1 ), second (AE 2 ) and third (AE 3 ) electric axes to coordinate the respective profiles of motion substantially constituting electric cams.