Unit for positioning a sheet of film to cover the tops of product groups

Abstract

A unit for positioning a sheet (1) of film (2) to cover the tops of product groups (3) comprises: a second roll (12) of film (2); a first carriage (13) that is slidably mounted on guide rails (14) running along an upper horizontal plane and is driven in both directions along the wrapping area (10) by motorized movement means (15); the first carriage (13) is equipped with a first gripper unit (16) designed to grip the free end of the film (2) and to unwind the film (2) for a predetermined length; film (2) cutting means (17) located in the vicinity of the second roll (12) and designed to separate the length of film thus unwound from the rest of the film (2); a second carriage (18) slidably mounted on the guide rails (14) in the vicinity of the cutting means (17); a second gripper unit (19) mounted on the second carriage (18), acting on the film (2) in such a way as to hold the sheet (1) at a second retention point when the cutting means (17) are activated; means (20) for coupling the second carriage (18) to the motorized movement means (15) in such a way that, when engaged, the two carriages (13, 18) can move together as one in order to position the sheet (1) centrally on the top surface of the product group (3).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The technical characteristics of the invention, with reference to the above aims, are clearly described in the claims below and its advantages are apparent from the detailed description which follows, with reference to the accompanying drawings which illustrate a preferred embodiment of the invention provided merely by way of example without restricting the scope of the inventive concept, and in which:

FIG. 1 is a schematic perspective view, with some parts cut away, of an apparatus for wrapping groups of products with film equipped with a unit according to the invention for positioning a sheet of film to cover the tops of product groups;

FIG. 2 is a schematic side view, with some parts cut away to better illustrate others, of the unit of FIG. 1 for positioning a sheet of film to cover the tops of product groups;

FIG. 3 is a schematic top plan view showing a detail A of the positioning unit of FIG. 1;

FIGS. 4 and 5 are schematic front views of the detail of FIG. 3 showing coupling means in two different working configurations;

FIGS. 6 to 8 are schematic top plan views, with some parts cut away to better illustrate others, of respective steps of positioning the sheet on the group of products using the unit illustrated in the drawings listed above.

Claims

1. A unit for positioning a sheet (1) of film (2) to cover the tops of product groups (3), the unit (4) being associated with an apparatus (5) for wrapping the product groups (3) with film (7) and comprising a frame (8) mounting at least one carriage (9) that moves relative to the group (3) of products to be wrapped with the film (7) to define a wrapping area (10), said carriage (9) in turn mounting at least one first roll (11) of film; the frame (8) also mounting one positioning unit (4) comprising at least: a second, horizontally positioned roll (12) of film (2);a first carriage (13) that is slidably mounted, on both sides, on guide rails (14) running along an upper horizontal plane and is driven in both directions along the wrapping area (10) by motorized movement means (15); the first carriage (13) being equipped with a first gripper unit (16) designed to grip the free end of the film (2) and to unwind the film (2) for a predetermined length dependent on the size of the product group (3);film (2) cutting means (17) located in the vicinity of the second roll (12) and designed to separate the length of film thus unwound from the rest of the film (2) to define the sheet (1), wherein the unit (4) comprises:a second carriage (18) slidably mounted on the guide rails (14) opposite the first carriage (13) and in the vicinity of the cutting means (17);a second gripper unit (19) mounted on the second carriage (18), acting on the film (2) in such a way as to hold the sheet (1) at a second retention point when the cutting means (17) are activated;means (20) for coupling the second carriage (18) to the motorized movement means (15) in such a way that, when engaged, the two carriages (13, 18) can move together as one in order to position the sheet (1) centrally on the top surface of the product group (3) to be covered.

2. The unit according to claim 1, wherein the second carriage (18) is equipped with means (21) for supporting the passing film (2) while it is being unwound by the first carriage (13).

3. The unit according to claim 1, wherein the second carriage (18) is equipped with means (21) for supporting the passing film (2) while it is being unwound by the first carriage (13); said supporting means (21) defining a contact base for the second gripper unit (19) enabling the latter to hold the sheet (1) at the second retention point when the cutting means (17) are activated.

4. The unit according to claim 1, where the motorized movement means comprise an endless belt (15) trained around one pair of wheels (22), one of which is power-driven, for each mounting guide rail (14), wherein the coupling means (20) are located at the two ends of the second carriage (18) and act on a section (15a) of the respective belts (15) with which the first carriage (13) is stably associated.

5. The unit according to claim 4, where each mounting rail comprises a C section beam 14, the lower horizontal section of the C slidably supporting respective first wheel unit (13a) and a second wheel unit (18a) associated with the ends of the first carriage (13) and second carriage (18), respectively, wherein each beam (14) accommodates an inner C-section beam (23) that is attached to the vertical section of the beam (14), is positioned above the area where the wheel units (13a, 18a) pass, and has sliding inside it the belt (15) section (15a) to which the first carriage (13) is attached.

6. The unit according to claim 5, wherein the coupling means (20) comprise a clamping member (24) located at and associated with each end of the second carriage (18) and at least partly and transversely engaging the respective inner C-beam (23) in such a way as to face both sides of the section (15a) of the belt (15); each of the clamping members (24) being acted upon by an actuator (25) designed to move the clamping member (24) between a configuration where the branch (15a) of the belt (15) is stably gripped so as to perform the joint movement with the first carriage (13), and a configuration where the belt section (15a) is released.

7. The unit according to claim 6, wherein each clamping member (24) comprises: a fixed contact base (26) attached to the second carriage (18), extending into the inner C-beam (23) below the area where the section (15a) of the belt (15) is engaged;a mobile claw (27) hinged at (28) to a support (29) of the second carriage (18) and extending into the inner C-beam (23); the outside free end of the claw (27) being acted upon by the actuator (25); one end of the actuator (25) being linked to the second carriage (18) while the other end is pivoted at (30) to a drive arm (31) attached to the mobile claw (27) in such a way as to enable the claw (27) to turn between a raised, idle position where the claw (27) is away from the section (15a) of the belt (15) and a lowered, working position where the claw (27) is in contact with the section (15a) which is positioned between the claw (27) itself and the fixed contact base (26).

8. The unit according to claim 7, wherein the mobile claw (27), in the idle position, is pressed against the upper side of the inner C-beam (23) with an inclined profile surface (27a) of it in such a way as to stop the carriage (18) at the corresponding position.

9. The unit according to claim 2, wherein the second gripper unit (19) comprises: at least one pair of the supporting means (21), each consisting comprising contact plates (21p) associated with the second carriage (18) and having an L-shaped portion protruding downwardly under the second carriage (18) in such a way that its horizontal section supports the longitudinal edge film (2) being unwound;a pair of vertical actuating pressers (32) positioned on the second carriage (18) in the vicinity of the plates (21p) in such a way as to face the horizontal section of the shaped portion, and mobile between an idle position where the working head (32a) of the rod is away from the horizontal section and a working position where the working head (32a) stops the film (2) between the head (32a) itself and the horizontal section of the plate (21p).