The invention is related to an installation for packing a product, such as one or more slices of a cheese product or a meat product, in film material, as defined in the preamble of claim 1. Such an installation is disclosed in US-A-3.016.673.
Said known type of film packing machines makes use of one roll of film. The packing principle is based on the movement of closing a book: the film is folded around the product. The product is first manually placed on the film. The machine then closes by one flap moving upwards and folding the film around the product. As soon as the flap has been completely closed, the pack is sealed on three sides by two fixed V-shaped elements, one of which is heated, pressing onto one another. The fourth side is closed by the fold. At the same point in time the film is also cut and transferred to the clamping device. The flap then opens again and the product can be removed.
A disadvantage of this form is that this type of machines cannot be incorporated in a production line. In addition it is a disadvantage that it is more difficult to make such a system suitable for various sizes of pack. Packing machines that can be used in a packing line have the characteristic that the product is fed into the machine via a conveyor belt. It is not possible in this way to pack foodstuffs in film only, without using a product carrier such as, for example, a plastic dish.
When packing products in film, with automatic throughout of the product, in general use is made of two rolls of film, the one roll being used for the bottom layer, whilst the other roll is used for the top layer. The consequence of this is that fusing the two layers of film together (known as sealing) has to be carried out on four sides of the product.
After packing, the film is then cut off the roll. Sealing on four sides has the consequence that at least 2 cm more film is required than when folding round the product.
In order to be able to process various sizes of the material to be packed, use can be made of a number of methods, such as the use of fixed, but interchangeable sealing bars or cutting between the two front edges and the side edges during sealing by means of sealing rollers.
Another problem with such machines is the interchanging of two rolls, as a result of which the risk of malfunctions becomes greater. Usually at least one of these rolls is not readily accessible.
The aim of the present invention is to provide an installation and a method for packing products in film which is not dependent on the way in which the product to be packed is fed (with or without product carrier) and is also able to process single item packs without additional film waste being generated as a result. Furthermore, the thickness of the material to be packed must not act as an impediment to the packaging itself.
Said aim is achieved by the features of the characterising portion of claim 1.
According to the present invention the film is used as transport medium and is transported such that the film is first pulled through and then pulled back over the product, so that the machine repeatedly returns to the starting position. This is in contrast to the method that is employed according to the state of the art of conventional flow packers. Compared with film packing machines which seal on 4 sides, this method will save at least 2 cm film per pack because one sealed seam (5 - 8 mm sealed seam plus 5 mm margin) is dispensed with because the seal at the front of the product is provided by a fold.
As a result of this method only one film roll has to be used for feeding material, as a result of which a saving in film can be achieved compared with a system with two rolls, where the rolls do not contain identical lengths of film. In addition, changing the stock roll will take less time.
The gripper means are fixed to a carriage which is movably accommodated on an auxiliary frame having a guide for the carriage, which auxiliary frame is attached to the base frame such that it can pivot about a horizontal pivot axis, which pivot axis is located at that end of the conveyor remote from the preparation surface, which auxiliary frame can be moved between a position in which the guide is parallel to the conveyor and a position in which the guide runs obliquely upwards.
Preferably, the lower sealing bar of the sealing installation is fixed with respect to the base frame and the upper sealing bar is accommodated on a tilting arm, the tilt shaft of which is located close to or coincident with the pivot axis of the auxiliary frame.
For the purpose of forming the quantity of film material required for one pack, with two pieces which can be sealed together, there is a carrier element between the preparation surface and the conveyor, which carrier element enables movement of the strip of film material transversely to the preparation surface, such that when a strip of film material is gripped in the gripper device this film material can be pulled into the form of a loop. The carrier element comprises a guide positioned transversely to the preparation surface, as well as a carriage that can be moved along said guide and which carries a horizontal roller positioned transversely to the conveyor.
By means of this carrier element, a first piece of film material can be drawn aside which subsequently can be positioned on top of the adjoining second piece of film material with the product thereon.
The invention also relates to a method for operating the installation described above, comprising the following steps:
The known folding method mentioned in the preamble has the disadvantage that it is not possible to place a new product ready when the pack is being sealed. In the preferred embodiment of the invention the installation is suitable for placing the film ready and transporting it while the pack is being sealed closed. This transport can also be used to move the product in small steps in the case of a combination with an automatic slicing machine, so that the cut slices can be put down stepwise. The layout of the film path has been so chosen that the machine can be positioned next to a fully automatic slicing machine in such a way that the film surface can be used as ejection surface.
The invention will be discussed in more detail below with reference to the drawings, in which:
Figure 1 shows the following components in a packing machine such as is constructed in an arbitrary embodiment:
A description of the mode of operation of the principle is now given below with reference to Figures 2 to 12.
Figure 2 shows the situation after manually inserting the film. Manual insertion of the film is facilitated in that the film can be guided through the feed opening (3) from the sides. After the film has been fed through the opening (3) it is guided around the rollers (4, 5, 7) to the supporting surface (6).
Figure 3 shows the situation immediately after starting the initialisation cycle. The operating flap of the sealing mechanism (13) has been pivoted downwards until it is just in contact with the bar transport system (9).
Figure 4 shows the situation where the film is clamped between the top and bottom sections. The operating flap of the sealing mechanism (13) has been pivoted downwards until the sealing U (12) is in contact with the bottom U (12a). The bar transport system (9) is carried along by the movement of this flap (13). After the top and bottom sections have been brought together a movement by the cutting mechanism (16) ensures that the film is cut off and is clamped in the film transport bar (10). At this point in time the machine has been initialised and the machine will continue with the operations in a normal cycle.
Figure 5 shows the situation where the film has been brought to the correct length by the film reversing system (8), so that the product to be packed can be placed on the table with the supporting surface (6).
Figure 6 shows that the operating flap of the sealing mechanism (13) with the sealing U (12) has been moved upwards, whilst the bar transport system (9) has remained in the lowest position. In this position, the packed product will be removed via the height-adjustable conveyor belt (11).
Figure 7 shows how the film is pulled through by the film transport bar (10) whilst, at the same time, the film reversing system (8) moves back so that the film on the supporting surface (6) does not move. By applying a difference in speed between the transport bar (10) and the film reversing system (8), it is nevertheless possible to make a suitable controlled movement when this is needed for positioning of the product to be packed. As soon as the film reversing system (8) has returned to the starting position, the system will wait until there is a product ready to be packed. In the interim the transport bar (10) can be used to move the product if the machine is coupled to, for example, an automatic slicing machine.
In Figure 8 the situation has been reached where the film has been pulled through to such an extent that the product is located above the discharge belt (11).
In Figure 9 the bar transport system (9) has been pivoted back into the starting position.
In Figure 10 the film transport bar has been transported back to the original position and the film has been pulled back with it over the product to be packed. This position corresponds to the situation in Figure 2 except that there is now a product ready to be sealed.
In Figure 11 the operating flap of the sealing mechanism (13) has been pivoted downwards until it is just in contact with the bar transport system (9). This situation is comparable to the situation in Figure 3.
In Figure 12 the product is sealed and at the same time is separated, by means of the cutting mechanism (16), from the roll of film and the film at the other side of the cut is again clamped in the film transport bar (10). At this point in time the machine has returned to the initialisation position and the machine will continue with the operations from Figure 6.