SEALING MACHINE WITH NO RESIDUAL FILM WASTE

This invention relates to a container sealing system available for any use that provides the application of a closing cover, which is usually constituted by a plastic film.

Mainstream sealing machines suffer the drawback of sealing containers with significant loss of film.

This invention proposes to avoid generating residual film waste by incorporating, in a position just before the film is draped upon every container for sealing, a system that cuts the film into pieces to a size suitable for every container.

Mainstream sealing machines come with a frame, an incoming conveyor belt, a intermittent belt, which moves a container to be sealed away from the following one, depending on the size and number of containers; according to EP 0334266 B2, a sealing station, consisting of an upper part and a lower part and an outgoing continuous-operation conveyor belt. When the number of containers to be sealed is reached, containers are taken by a gripping device and moved to under the sealing station. After containers are sealed, the gripping device conveys containers onto the second continuous-operation conveyor belts. The system is typically combined with a coil of film web for the sealing of containers. This film web runs through a space between the containers and the upper part of the sealing station and closes containers. As already commented, this system generates an excess of sealing film web, which is wound round an additional coil placed downstream of the machine. This invention incorporates, within the frame (1), a new device, which consists of a shuttle (12) equipped with as many moving plates (13) as the number of containers to be sealed, preventing any excess film.

The shuttle (12) is associated with a cutting assembly (1 1). In standard applications, 20% to 40% of film is waste material.

This invention provides the cutting of film into pieces just before the film is transferred to under the upper mould of the sealing station (6) by means of the aforementioned cutting assembly (1 1), which operates on the moving plates (13). Every piece of film is first cut parallel and transversally to the motion of the machine and the first intermittent-operation conveyor belt (3) and according to the size and number of containers to be sealed, and subsequently moved inside the sealing station by means of the shuttle (12) and draped over containers that have been previously placed on the lower mould of the sealing station (5), without generating any film waste.

The following step regards sealing. The cut parallel to the motion of containers is obtained with a fixed longitudinal blade (10), which is positioned upstream of the moving plates (13). The film is transversally cut on moving plates (13) by means of a cutting assembly (11), which cuts the film along the corresponding side rims of the moving plates (13), the surface of which corresponds to the surface of every container to be sealed.

In particular, this procedure is performed according to these steps.

A moving gripper (14) moves the web from the film coil (8) and the film uncoiling device (9) to under the cutting assembly (1 1) and, accordingly, above the shuttle (12). During the transfer of film, the fixed longitudinal blade (10) cuts the film in the middle, with a cut parallel to the direction of movement of containers and the film itself.

By means of a vacuum pump, vacuum is generated on the surface of moving plates (13) that are positioned on the shuttle (12) so that the film adheres to the moving plates (13) and remains fixed.

Now, the cutting assembly (1 1) is driven and cuts the film perpendicular to the direction of movements of containers, creating pieces of film in a size desired and suitable for every container to be sealed. These pieces of film adhere to the moving plates (13) of the shuttle (12) thanks to the generation of vacuum. So, moving plates (13) are driven and spaced from each other, as shown in the comparison between Figure 5 and Figure 6, so that pieces of film are moved to the longitudinal and transversal positions of the upper mould of the sealing station (6) by the shuttle (12).

Meanwhile and in a completely independent way, containers to be sealed, coming from the incoming conveyor belt (2), are positioned onto the first intermittent- operation conveyor belt (3) and, subsequently, moved onto the lower mould of the sealing station (5) by means of the gripping device (7).

At this point, the shuttle (12) moves to the sealing station with the pieces of film cut. Simultaneously, the moving gripper (14) installed on the shuttle (12) transfers the web of film from the film coil (8) and the film uncoiling device (9) to under the cutting assembly (11). Pieces of film are transferred from the shuttle (12) to the upper mould of the sealing station (6), closing the vacuum in the moving plates (13) of the shuttle (12) and generating the vacuum within the mould of the sealing station (6).

The empty shuttle (12) moves back to the cutting assembly (11) where it starts the initial cycle again.

The lower mould of the sealing station (5) moves to the upper mould of the sealing station (6) and completes the sealing process.

Subsequently, the lower mould of the sealing station (5) opens and sealed containers are ready to be transferred onto the outgoing belt (4) by means of a gripping device.

The preferred embodiment includes the following elements:

I . frame

2. incoming conveyor belt

3. first intermittent-operation conveyor belt

4. outgoing conveyor belt

5. lower mould of the sealing station

6. upper mould of the sealing station

7. gripping device

8. film web coil

9. film uncoiling device

10 longitudinal blade

I I. cutting assembly

12. shuttle 13. moving plate

14. moving gripper