EP0994021B1 - Method and device for packaging products, and packaging tray therefor - Google Patents

Abstract

The packaging of products (P) in heat formed food trays from thermoplastic or thermoformable material (1) provided in reels comprises: (1) thermoforming (4) cavities (B) and caps (A) associated on the same band; (2) cutting three sides around (B) keeping (A) and (B) attached; (3) filling (10) the cavities (B) with products (P); (4) folding (12) the caps (A) over the cavities (B); and (5) heat sealing (14) (A) and (B). Independent claims are also included for: (1) a packaging device; and (2) a food tray prepared according the above packaging method.

Description

The invention relates to a process for packaging products, including food, chemical or pharmaceutical products, to a device for implementing said method, as well as a tray of packaging of products.

We know many processes and packaging equipment of products. Usually two rolls of material strips are used deformable, the first strip being intended to be shaped for constitute cavities and the second strip being intended to be welded to the perimeter of the cavities to form a seal and a sealed assembly protecting the food, chemical or pharmaceutical products contained in the cavities.

Product storage can be extended by packaging products in vacuum or inert atmosphere, by injection of a neutral gas at the welding station.

The document EP 0 652 155 A1 describes a method, a device and a packaging container for food, chemical or pharmaceuticals using a first strip of thermoplastic material or thermoformable and a second strip of thermoplastic material or heat-sealable.

The invention aims to improve the prior art, by allowing using only a single strip of thermoplastic material or thermoformable for packaging products in sealed trays.

The subject of the invention is a method according to claim 1.

• le procédé comporte en outre une étape de prédécoupe entre cavités et couvercles associés, pour laisser subsister une ou plusieurs attaches formant charnière de rabattement ;
• le procédé comporte en outre une étape de découpe des lisières bordant les cavités thermosoudées aux couvercles, pour libérer individuellement une ou plusieurs barquettes contenant lesdits produits.

According to other characteristics of the invention:

• the method further comprises a step of precut between cavities and associated covers, to allow one or more fasteners to form a hinge;
• the method further comprises a step of cutting the selvedges bordering the heat-sealed cavities with the covers, to individually release one or more trays containing said products.

The invention also relates to a device for conditioning products in thermoformed trays, using a single strip of thermoplastic or thermoformable material, comprising means for thermoforming of cavities and associated covers in said strip, means of cutting on three sides around the covers, means of loading the cavities with products, means for folding the covers on the cavities and means for heat sealing the covers to cavities for constituting trays containing said products;

• le dispositif comporte des moyens de prédécoupe entre cavités et couvercles associés pour laisser subsister une ou plusieurs attaches formant charnière de rabattement.
• le dispositif comporte des moyens de découpe des lisières bordant les cavités thermosoudées aux couvercles.
• les moyens de rabattement des couvercles sur les cavités comprennent au moins un doigt rotatif escamotable.
• les moyens de rabattement des couvercles sur les cavités sont prédéterminés pour relever les couvercles et les rabattre d'un angle supérieur à 90 degrés d'angle.

According to other characteristics of the invention:

• the device comprises means for precut between cavities and associated covers to allow one or more fasteners to form a hinge.
• the device comprises means for cutting the selvedges bordering the heat-sealed cavities with the covers.
• the means for folding the covers over the cavities comprise at least one retractable rotary finger.
• the means for folding the covers over the cavities are predetermined to raise the covers and fold them down at an angle greater than 90 degrees of angle.

The invention also relates to a packaging tray of products obtained by implementing a method according to the invention in using a device according to the invention.

According to other features of the invention, the cavity and the cover have edges with distinct contours, so that provide two tabs capable of being separated to facilitate the opening of the tray.

• la figure 1 représente schématiquement une vue en coupe longitudinale d'un dispositif selon l'invention,
• la figure 2 représente schématiquement et partiellement une vue de dessus d'un dispositif selon l'invention,
• les figures 3 à 8 représentent schématiquement les étapes successives d'un procédé de conditionnement selon l'invention,
• la figure 9 représente schématiquement une vue de dessus explicitant la mise en oeuvre de l'invention,
• la figure 10 représente schématiquement une vue en coupe transversale d'une barquette de conditionnement selon l'invention,

The invention will be better understood from the description which follows, given by way of nonlimiting example with reference to the appended drawings, in which:

• FIG. 1 schematically represents a view in longitudinal section of a device according to the invention,
• FIG. 2 schematically and partially represents a top view of a device according to the invention,
• FIGS. 3 to 8 schematically represent the successive stages of a packaging process according to the invention,
• FIG. 9 schematically represents a top view explaining the implementation of the invention,
• FIG. 10 schematically represents a cross-sectional view of a packaging container according to the invention,

Referring to Figures 1 and 2, a device according to the invention is consisting of online assembly of functional modules supported by load-bearing frames for treating a single strip of thermoplastic material or thermoformable unwound from a roll 1.

The end of the strip wound on the roll 1 is driven by horizontal chains on the links of which clamps are mounted gripping the strip of thermoplastic material, so as to cause the strip of thermoplastic material in discontinuous steps corresponding to the advancement of the strip of the roller in the successive cycles of the process according to the invention.

The means of gripping and driving the first strip of thermoplastic material constituted by the horizontal chains are in themselves known, in particular by document FR 2.027.741 in the name of applicant for this application, and do not require further description Detailed.

The thermoplastic strip of roll 1 is unwound flat to arrive in a first zone 2 adapted to receive a device 3 of preheating of the strip of thermoplastic material. Preheating is performed for example by means of one or more metal plates having good thermal conductivity. In at least one of metal plates is embedded a heating element, for example a armored resistor electrically insulated from the metal plate.

Leaving zone 2 reserved for preheating, the strip of material thermoplastic advances in successive steps in a thermoforming zone 4 comprising a thermoforming module 5.

The thermoforming technique used in zone 4 of thermoforming is for example the thermoforming technique known as "negative" simple ", the most common technique in which we first heating the strip of material to be thermoformed by applying it to the contact of a heating plate 5a, then the actual deformation by blowing compressed air through an upper heating plate 5b provided with this effect of appropriate orifices.

Alternatively, the thermoforming module 5 could comply to the technique known as "negative with mechanical assistance", technique in which the film is heated by a contact on either side of this by sandwiching between two thermally regulated plates possibly at different temperatures, then by lowering a piston for example metallic to pre-stretch the strip of performed material and finally by plating the thermoplastic strip on the mold by air injection or compressed gas through the piston provided for this purpose with suitable orifices.

Finally, in the case of more rigid materials, module 5 of thermoforming preferably conforms to the technique known as "positive with bubbling ", a technique in which heating is first carried out contact between two thermally regulated plates, then the strip is deformed of thermoplastic material by suction in the lower part of the tooling so as to pre-stretch the thermoplastic film or strip and finally the draping, that is to say the plating of the film on the mold lowered for this purpose or at the level of the thermoplastic strip. In this "bubbling" technique known per se, vertical walls of advantageous shapes are advantageously obtained regular with thick packaging container angles sufficient to avoid any subsequent drilling.

The main thing is that we perform during thermoforming of the pairs successive cover A and cavity B associated in the strip of material thermoformable unrolled from the roll 1.

In the nonlimiting example shown, the thermoforming line is constituted in double line allowing the simultaneous conditioning in parallel of two trays.

At the exit of zone 4 of thermoforming, a zone 6 of precut transverse is provided to constitute a hinge between cavity B and cover A. A knife 7a and an anvil 7b cooperate for this purpose to make a cross section to the direction of advancement of the strip leaving two or three fasteners between cavity B and cover A.

A cutting area 8 on three sides is adjacent to area 6 of pre-cut to make a cut surrounding each cover A out of three sides by means of a knife with two blades 9a, 9b having a contour in U.

Each hollow cover A is thus detached from the strip on three sides by only being connected to the strip of thermoformable material by the aforementioned fasteners.

Guide rails or pads, not shown, are advantageously provided to support and guide the covers A driven by advancing in successive steps the strip of thermoplastic material.

On leaving the U-shaped cutting area 8 on three sides, the cavities B are filled in a zone 10 for filling products to be packaged, or manually, either by 11 pouring or dosing devices.

After filling, the covers A are folded down over the cavities B around the aforementioned fasteners in a drawdown zone 12 thanks to a medium 13 lid flap.

As a means 13 for lid closing, it is possible to envisage fingers rotary swivels intended to raise the bottoms of covers A at an angle greater than 90 degrees, for example of the order of 120 degrees, sufficient for obtain the closure of cover A by gravity fallout around the remaining fasteners.

In FIG. 2, in which the mechanical elements located above of the thermoformable strip have not been shown for clarity, we finds that the folding of the covers A in the area 12 shows contours cut C in the thermoformable strip.

The covers A folded down and cavities B are then entrained in a welding zone 14, in which two welding bells 15a, 15b come apply to the edges of the covers A and cavity B to weld them so as to make a tight junction.

As a type of weld that can be used, it is possible to envisage a flat bead, radiated bead weld, flat weld, weld with a bead or a diamond point weld. In zone 14, the module heat sealing 15a, 15b optionally incorporates an underlayer vacuum depending on the nature of the materials to be welded and the products to be contain (indeed, for certain emulsified products or with a high content of liquid, you can only carry out a partial vacuum under penalty of boiling the product to be packaged).

• le système à réinjection par buse dans lequel on maintient le couvercle A en position entrebâillée pour permettre la réinjection de gaz et dans lequel on utilise une buse située à l'intérieur de l'outillage de soudure et effectuant la réinjection de gaz à l'intérieur de la cavité B
• ou alternativement la technique de réinjection comme dite "par pastillage", dans laquelle la bande thermoformée préalablement découpée par un module "de pastillage" permet d'effectuer une réinjection de gaz au moyen de conduits situés en position centrale ou en position latérale du moule de soudure, conduits par lesquels le gaz de réinjection débouche à travers l'emplacement en forme de pastille découpé dans la bande thermoformée.

The heat sealing module 15a, 15b can also integrate, in addition to or in replacement of the vacuum module, a reinjection module operating according to one or other of the following systems:

• the nozzle re-injection system in which the cover A is kept in the ajar position to allow gas re-injection and in which a nozzle is used located inside the welding tool and carrying out the gas re-injection inside from cavity B
• or alternatively the reinjection technique as said "by tableting", in which the thermoformed strip previously cut by a "tableting" module makes it possible to carry out a gas reinjection by means of conduits situated in the central position or in the lateral position of the mold. welding, conduits through which the reinjection gas emerges through the pellet-shaped location cut out of the thermoformed strip.

Leaving the zone 14 of heat sealing, the trays are cooled sealed containing the product packaged in a zone 16 of cooling, in which two cooling bells 17a, 17b cool the trays, and in particular the tray edges which have just been welded in zone 14.

At this stage, the cooled trays are still attached to the thermoplastic strip, because the edges of cavities B have not been detached from the thermoplastic strip.

This separation is carried out in the final cutting zone 18 at by means of cutting discs 19a, 19b counter-rotating. Discs 19a, 19b cut the edges of the edges of cavities A, which are wound on recovery drums 20.

Due to the transverse separations corresponding to the contours cut, just use a longitudinal slicing (in the direction of scrolling of the thermoplastic strip) by means of discs 19a, 19b, for separate each container of conditioned product individually and dispose of it in the direction of the arrows 21.

Referring to Figures 3 to 8 showing successive views of the thermoplastic strip seen in cross section, there is shown on the figure 3 the thermoforming phase of zone 4 carried out in module 5 to simultaneously constitute a cavity B and a cover A in the strip of thermoplastic material advancing step by step in advance predetermined according to the dimensions of the corresponding mold.

In FIG. 4, the transverse cutting of zone 6 is carried out by means of the punch 7a and the anvil 7b, so as to leave some weak attachments between cover A and associated cavity B.

In FIG. 5, the surrounding U-shaped cut is made of the zone 8 on three sides using the U-shaped punch 9a and the anvil 9b, so as to completely detach the three sides corresponding to the edge outside of covers A.

In FIG. 6, the cavities B are filled with a product P. The product P at least partially fills each cavity B without however overflow from it. Various filling means can be provided for filling station 10, for example the use of a device 11 for filling of product P.

In FIG. 7, the drawdown of the covers A on the cavities B around the attachment points materializing a hinge. A folding means 13, for example a push finger retractable at each step in advance, preferably acts on the cover A, so that the edges of cover A are applied to the cavity edges B.

In Figure 8, is carried out at the station 14 of heat sealing a possible evacuation or injection of neutral gas at least one nozzle 22 injection through the ajar opening of the tray, and then heat-seal the edges using the bells 15a, 15b of heat sealing.

Finally, the welded trays and in particular their edges are cooled. welded to the cooling station 16 using the bells 17a, 17b of cooling.

FIG. 9 represents a preferred embodiment of the invention and illustrates with references identical to those of the preceding figures the setting implementation of the invention by folding the covers A over the cavities B filled with product P, so as to release in the thermoformed strip contours C cut out of separation between successive trays.

FIG. 10 schematically represents an embodiment preferred tray according to the invention.

The cover A has rectangular flanges 22 which protrude rounded edges of cavity B while cavity B has a tongue 23 able to be moved away from the corner 22 to allow by simple pull easy opening of the tray.

The invention described with reference to a particular embodiment does not is in no way limited, but on the contrary covers any modification of form and any variation in implementation within the scope and spirit of the invention, allowing the use of a single strip of thermoformable material for packaging a product in trays, each assembled in such a way waterproof from a cavity and a cover.

Claims (10)

1. Method for packaging products (P) in heat-moulded trays using a single strip of thermoplastic or heat-mouldable material (1), including steps (4) of heat-moulding associated lids (A) and cavities (B) in said strip, of cutting (B) on three sides around the lids (A), the cavities remaining integral with said strip, of charging (10) the cavities (B) with products (P), of folding down (12) the lids (A) over the cavities (B) and of heat-welding (14) the lids (A) to the cavities (B) in order to form trays containing said products (P).
2. Method according to Claim 1, including, also, a step (6) of preliminary cutting between associated lids (A) and cavities (B) in order to leave one or more attachments remaining, forming a folding-down hinge.
3. Method according to Claim 1 or Claim 2, including, also, a step (18) of cutting the edges bordering the cavities (B) heat-welded to the lids (A) in order individually to release one or more trays containing said products (P).
4. Device for implementing the method according to Claim 1, including means (5) for heat-moulding associated lids (A) and cavities (B) in said strip, means for cutting on three sides (9a, 9b) around the lids (A), means (11) for charging the cavities with products (P), means (13) for folding down the lids (A) over the cavities (B) and means for heat-welding the lids (A) to the cavities (B) in order to form trays containing said products (P).
5. Device according to Claim 4, including means (7a, 7b) for preliminary cutting between associated lids (A) and cavities (B) in order to leave one or more attachments remaining, forming a folding-down hinge.
6. Device according to Claim 4 or Claim 5, including means (19a, 19b) for cutting the edges bordering the cavities (B) heat-welded to the lids (A).
7. Device according to any one of Claims 4 to 6, in which the means (13) for folding down the lids (A) over the cavities (B) comprise at least one retractable rotary finger.
8. Device according to any one of Claims 4 to 7, in which the means (13) for folding down the lids (A) over the cavities (B) are pre-set in order to lift the lids and fold them down at an angle greater than 90° of angle.
9. Tray, for packaging products, obtained by implementing a method according to any one of Claims 1 to 3 or by using a device according to any one of Claims 4 to 7.
10. Tray according to Claim 9, characterized in that the cavity (B) and the lid (A) have rims that have distinct contours so as to form two tabs (22, 23) suitable for being moved apart in order to facilitate opening of the tray.

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