EP0516556B1 - Method of thermoforming and possible laser packaging of containers and machine therefor - Google Patents

Abstract

The present invention relates to a method and a machine for thermoforming and possible later packaging of containers. The machine according to this invention comprises stations (9, 10), for thermoforming containers, which are followed by a plurality of packaging stations (12, 13, 14) for, in particular, filling and closing the containers, and is characterised in that, upstream of the thermoforming stations, provision is made for a station (1) for cutting a strip (2) of thermoformable plastic material into successive strip portions (5) and in that the thermoforming and packaging stations are arranged around a plate (6) driven, step by step, in rotation and supporting strip portions (5). This machine applies, for example, to the thermoforming and packaging of cups made from plastic material which are to contain a foodstuff. <IMAGE>

Description

The present invention essentially relates to a process for thermoforming and possible subsequent packaging of plastic containers such as for example cups or trays.

It also relates to a machine for the implementation of this process.

Machines are already known for manufacturing containers by thermoforming from a continuous sheet of plastic material with one or more layers in the form of a coil facilitating transport and storage.

In conventional machines, the thermoforming operation generally consists of gradually unwinding the plastic sheet, heating it using various means, and using the action of compressed air and / or vacuum to press the hot and malleable sheet against the walls of a mold, thereby making it possible to form containers having the shape of the mold.

Certain known thermoforming machines not only make it possible to manufacture containers, but also to condition them, that is to say fill them with any product, and to close them.

In all cases, the various thermoforming and possibly packaging operations are carried out on so-called "in-line" machines which use a strip of continuous material unwound from a reel and which is cut only at the last operation to separate the containers or groups of containers from each other. Thus, on these machines, the plastic sheet advances step by step under the action for example of chains with clamps so that all the desired operations are carried out successively.

However, these machines are very difficult to drive and have drawbacks. Indeed, the continuous plastic sheet, heated in places, cooled in others, undergoes uncontrollable shrinking phenomena which exert variable stresses on the belt handling system. The pitch of the containers formed is therefore variable and there is frequently interference between the containers themselves and certain tools such as, for example, those constituting the station for closing containers by thermocell or the cutting station at the end of the line. . This results in significant productivity decreases due to the frequent interventions of operators on the machine to constantly ensure perfect adjustment of the latter and also because the containers themselves can be damaged due to the abovementioned withdrawal phenomena.

Also, the present invention aims to remedy these drawbacks by proposing a method and a machine for thermoforming and possible subsequent packaging of containers which not only allow a high production rate of thermoformed and conditioned containers without incidents, but which do not risk in no way to damage the containers during successive thermoforming and packaging operations.

To this end, the subject of the invention is a process for thermoforming and possible subsequent packaging of containers such as cups or trays, characterized in that it consists in cutting a strip or the like of thermoformable plastic material into successive strip sections which are separately subjected to a thermoforming operation to form in each strip section one or more receptacles which possibly then undergo packaging operations such as in particular filling and closing along a substantially circular trajectory.

According to another characteristic of this process, a sterile radial air flow is sent from substantially the center of the aforementioned circular path towards in particular the thermoforming and container packaging stations, so that all the operations are carried out in one aseptically.

This invention also relates to a machine for implementing the method meeting one or the other of the above characteristics, this machine being of the type comprising at least one station for thermoforming containers followed by a plurality of stations. packaging in particular for filling and sealing said containers, and being characterized in that upstream from the thermoforming station there is provided a station for cutting a strip of thermoformable plastic material into successive strip sections and in that said thermoforming stations and packaging are arranged around a plate driven in step-by-step rotation and supporting said strip sections.

According to another characteristic of this machine, the aforementioned plate is crossed in its center by a vertical duct provided with radial openings or the like for sterile air outlet in the direction of the thermoforming and packaging stations in the form of a flow of substantially horizontal sterile air.

According to yet another characteristic of this machine, the aforementioned conduit is interposed between a plate, in the upper part, forming the roof of the machine and, in the lower part, a step-by-step drive mechanism for the aforementioned plate.

Thus, any fallout of dust or particles which may contaminate the thermoforming and packaging areas will be advantageously avoided.

• La figure 1 est une vue schématique et en plan de dessus d'une machine conforme aux principes de l'invention.
• La figure 2 est une vue schématique et en coupe verticale de cette machine, suivant la ligne II-II de la figure 1.

However, other advantages and characteristics of the invention will appear better in the detailed description which follows and which refers to the appended drawings, given by way of example, and in which:

• Figure 1 is a schematic top plan view of a machine according to the principles of the invention.
• FIG. 2 is a schematic view in vertical section of this machine, along line II-II of FIG. 1.

Referring in particular to this FIG. 1, it can be seen that a machine according to this invention comprises, at the entrance to the machine, a cutting station 1 comprising for example a movable blade and allowing cutting along line 3 of a strip 2 of thermoformable plastic, said strip being wound on a reel 4 of axis XX ′ and constituting after cutting a plurality of strip sections 5 which are conveyed successively and by any suitable means to a turntable 6 whose periphery can be equipped with a plurality of supports 6a for receiving the strip sections 5.

Around the plate 6 driven in step-by-step rotation along the arrow F (Figure 1) by means of a stepping drive mechanism marked schematically at 7 in Figure 2, are distributed a plurality of stations known per se for thermoforming and packaging of containers R.

These stations successively include, and according to an exemplary embodiment, a station 9 for heating a strip section 5, a station 10 for forming containers by the action of compressed air and / or vacuum, said station forming possibly associated with a station 11 for printing and / or decorating the containers formed, a station 12 for dosing or filling the containers, possibly another station 13 for dosing or filling the containers with a product other than that of the station 12, and a station 14 for closing the containers by heat-sealing lids, for example, this station possibly also forming a station for cutting filled and closed containers. Schematically shown at 15 is a station for storing lids in a stack or in a band which are conveyed to station 14, and in 15a a conveyor or similar means allowing the containers R to be evacuated from the machine.

Between the aforementioned stations 9, 10, 12, 13 and 14, there are a number of free stations marked schematically at 16 and allowing correct operation of the machine, that is to say facilitating access to the different stations or the addition of annex doors.

It is therefore understood from the above that this machine works from strip sections 5 which are sectioned at 3 at the entrance to the machine and as it operates, that is to say from the step-by-step rotation of the plate 6. Consequently, the withdrawal phenomena can only concern a small element or section of strip and the harmful interferences between the various stations are therefore eliminated, which would necessarily occur if a strip were used continuous thermoformable plastic material as was the case in the prior art. In addition, the fact of working with separate strip sections and no longer with a continuous plastic strip requiring an "in-line" machine structure, makes it possible to carry out the various thermoforming and packaging operations on a tray, ie that is to say with a precision and reliability which are much greater than with in-line machines generally using conveyor belts.

It can also be seen in FIGS. 1 and 2 that the machine according to this invention is equipped with a vertical duct 17 provided in its wall with openings 18. This duct 17 is supplied with sterile air as shown diagrammatically at 19 in FIG. 2 The vertical air duct 17 passes through its center the turntable 6 which for this purpose has an opening 20.

Thus, as can be understood, and as shown by arrows in FIGS. 1 and 2, sterile air will be emitted from the orifices 18 of the duct 17, and this radially in the direction of the abovementioned thermoforming and packaging stations so that the various thermoforming and packaging operations will advantageously be carried out in a sterile atmosphere.

In addition, as it clearly appears in FIG. 2, the conduit 17 is interposed between a plate 21, in upper part, forming the roof of the machine and, in the lower part, the mechanism 7 for driving in step-by-step rotation of the plate 6.

Any fallout or penetration of dust or particles to the packaging and thermoforming stations will therefore be prevented. This means that the horizontal sterile air flow produced by the conduit 17 will be protected against any risk of external contamination.

A process and a machine have therefore been produced according to the invention which allow the manufacture by thermoforming and packaging of containers in a reliable and precise manner thanks to the use of successive and precut strip sections, the thermoforming operations and packaging is also optionally and advantageously carried out in a sterile atmosphere.

Of course, the invention is in no way limited to the embodiment described and illustrated, which has been given only by way of example.

Thus, a combination of packaging stations other than that described could be provided on the machine.

Claims (5)

1. Method of thermoforming and possible later packaging of containers such as goblets or boat-shaped small containers, characterized in that it consists in cutting out a strip or the like (2) of plastic material adapted to be thermoformed to provide successive sections (5) of the strip which are separately subjected to an operation of thermoforming so as to form in each section of the strip one or several containers which then are possibly subjected to some packaging operations such as notably filling and closing along a substantially circular path.
2. Method according to claim 1, characterized in that a radial sterile air flow is sent from substantially the center of the said path towards the stations for thermoforming (9, 10) and packaging (12, 13, 14) the containers.
3. Machine for carrying out the method according to claim 1 or 2, and of the type comprising at least one station (9, 10) for thermoforming the containers (R) followed by a plurality of packaging stations (12, 13, 14) for notably filling and closing said containers, characterized in that a station (1) for cutting out a strip (2) of plastic material adapted to be thermoformed for providing successive sections (5) of the strip is provided upstream the thermoforming station (9), and in that said thermoforming and packaging stations are arranged around one plate (6) driven in rotation step by step and bearing said strip sections.
4. Machine according to claim 3, characterized in that a vertical duct (17) provided with radial openings or the like (18) for the exit of sterile air towards the stations (9, 10) of thermoforming and packaging (12, 13, 14) under the form of a substantially horizontal sterile air flow passes through the center of said plate (6).
5. Machine according to claim 3 or 4, characterized in that the said duct (17) is interposed between one plate (21) forming a top wall for the machine in its higher portion, and a mechanism (7) for driving step by step the plate (6) at the lower portion of the machine.

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