EP0593109B1 - Machine for closing a container such as a semi-rigid tray, by means of a cover - Google Patents

Description

The invention relates to a machine for closing a container, such as a container made of a semi-rigid material, by means of a cover. It is particularly applicable to the closing of trays containing fruit.

At present, there are automated machines for closing trays of fruit by means of lids which snap onto said trays. Such machines include a latching station to which the trays are routed and at the level of which a cover is lowered and the latter pressed on said tray in order to obtain the closing thereof. The disadvantage of such machines lies in the fact that the trays filled with fruit are frequently deformed by the latter. As a result, these trays no longer have an upper face of a form strictly conjugate with that of the covers, and when the latter are brought into contact with said trays, on the one hand, they can no longer be assembled with the latter and, d On the other hand, they frequently come into contact with the fruits they spoil.

To overcome this drawback, the applicant has developed a machine, described in patent application FR-A-91.08573 (not published on the date of filing of this application), in which the container is initially belted, guaranteeing against any deformation of the latter, then moved upwards until it meets the cover itself, surrounded by a stirrup.

When the container is closed, the latter and the cover therefore occupy perfectly defined relative positions. As moreover, the container cannot deform, the closing operation is carried out with great reliability.

However, the downside of this machine lies in the fact that it operates discontinuously, the closing operation necessitating stopping the translation of the containers, then a vertical movement of the latter. Therefore, the production rates of such a machine are relatively low.

The present invention aims to overcome this drawback and aims to provide a machine offering the advantages of the above described, namely mainly the possibility of carrying out with great reliability the operation of closing a container, and also operating , with a high production rate (see also as an example the machine described in EP-A-0 170 627).

To this end, the invention relates to a machine for closing a container, such as a container made of semi-rigid material, having the characteristics defined in claim 1.

According to the invention, and during its progression, the container is therefore initially encircled, thus guaranteeing against any deformation thereof. In a second step, this container encounters a cover positioned so as to be driven by this container and to come to deposit on the latter without slowing down its translation speed. Finally, the assembly is carried out during the passage of the container / cover assembly in line with the conforming means of conjugate shape of the cross section of the cover.

Consequently, and first of all, the various operations leading to the closure of the container are carried out continuously, making it possible to obtain a very high yield. For example, a machine for closing conventional fruit trays has a yield of the order of 3,000 trays / hour.

In addition, during these operations, the container surrounded by a shaper cannot therefore be deformed and the closing operation is carried out with great reliability.

It should be noted, moreover, that the design of this machine makes it possible to use it with containers of different size and shape by providing for this purpose removable conformers of combined shapes and dimensions of the different models of containers and lids.

• les moyens d'entraînement des conformateurs sont disposés de façon à déplacer ces derniers selon une trajectoire horizontale située à une hauteur adaptée pour que lesdits conformateurs viennent entourer les conteneurs dans une portion intermédiaire de leur hauteur,
• les moyens de convoyage comportent une piste sur laquelle se déplacent les conteneurs, ladite piste étant interrompue en amont du point d'amenée des couvercles de façon que chaque conteneur subisse un déplacement vers le bas par rapport au conformateur l'entourant, amenant ledit conteneur à se retrouver ceinturé à proximité de sa face supérieure.

According to another characteristic of the invention:

• the shaping drive means are arranged so as to move these the latter along a horizontal trajectory situated at a height suitable for said conformers to surround the containers in an intermediate portion of their height,
• the conveying means comprise a track on which the containers move, said track being interrupted upstream of the point of supply of the covers so that each container undergoes a downward movement relative to the surrounding shaper, bringing said container to find yourself belted near its upper face.

In addition, according to a preferred embodiment, the means for driving the conformers comprise two support chains of said conformers driven in a closed loop around pinions with vertical axes, said chains each supporting one of the elements of the conformers and being arranged in parallel one relative to each other so that said elements cooperate with a view to driving the containers.

Furthermore, each shaping element advantageously consists of two L-shaped parts arranged opposite one another and each carried by a support member secured to at least one link of the drive chain.

In addition, according to another characteristic of the invention, the support member of each part of a shaping element comprises a plate secured to at least one link of the chain by means of an axis, and provided with at least a finger protruding on the underside. In addition, a guide track, arranged under each chain, comprises a support surface capable of allowing the sliding of the plates, in which is formed a groove for guiding the fingers of said plates.

When it is used for closing the containers by means of lids provided with a peripheral rim, this machine also preferably comprises conforming means comprising a centering coil comprising sides adapted for grip the cover and apply pressure on the edge of the latter.

• les moyens d'amenée des couvercles sont adaptés pour les présenter dans une position telle que leurs moyens d'encliquetage amont soient disposés en correspondance avec les moyens d'encliquetage amont des conteneurs venant en contact avec lesdits couvercles,
• les moyens conformateurs comportent, en aval de la bobine centreuse, un étrier de section conjuguée de la section transversale d'un couvercle, et des moyens d'entraînement dudit étrier selon un axe vertical, aptes à déplacer ce dernier de façon qu'il vienne exercer une pression sur le couvercle, au niveau de l'extrémité aval de ce dernier, en vue d'entraîner l'assemblage des moyens d'encliquetage aval.

In addition, when using this machine for the assembly of lids and containers provided with latching means respectively arranged at the end faces said upstream and downstream of said lids and containers, and advantageously :

• the lids supply means are adapted to present them in a position such that their upstream latching means are arranged in correspondence with the upstream latching means of the containers coming into contact with said lids,
• the shaping means comprise, downstream of the centering coil, a stirrup of conjugate section of the cross section of a cover, and means of driving said stirrup along a vertical axis, able to move the latter so that it comes exert pressure on the cover, at the downstream end of the latter, in order to cause the assembly of the downstream latching means.

• une rampe inclinée dotée de moyens de guidage latéral adaptés pour centrer les couvercles par rapport aux flancs de la bobine centreuse,
• un magasin de couvercles empilés les uns sur les autres, disposé vers l'extrémité haute de la rampe,
• des moyens de préhension aptes à saisir un à un les couvercles empilés et à les déposer sur la rampe,
• des moyens d'arrêt escamotables disposés vers l'extrémité inférieure de la rampe, agencés pour stopper la descente du couvercle se trouvant en tête de ligne et se présentant au niveau de ladite extrémité,
• et des moyens d'entraînement du couvercle stoppé par les moyens d'arrêt escamotables, adaptés pour amener ledit couvercle dans la position appropriée pour permettre son entraînement par un conteneur.

Furthermore, according to another characteristic of the invention, the means for supplying the covers comprise:

• an inclined ramp provided with lateral guide means adapted to center the covers with respect to the sides of the centering coil,
• a store of covers stacked on top of each other, arranged towards the upper end of the ramp,
• gripping means capable of gripping the stacked lids one by one and depositing them on the ramp,
• retractable stop means arranged towards the lower end of the ramp, arranged to stop the descent of the cover located at the head of the line and occurring at said end,
• and means for driving the cover stopped by the retractable stop means, suitable for bringing said cover into the appropriate position to allow it to be driven by a container.

• les moyens d'entraînement du couvercle se trouvant en tête de ligne comprennent une plaque-poussoir agencée pour venir en prise avec ledit couvercle, et des moyens de déplacement de ladite plaque-poussoir aptes à la déplacer longitudinalement le long de la rampe et orthogonalement au-dessus de celle-ci,
• un organe de butée flexible est disposé de façon à interdire un glissement éventuel d'un couvercle amené en position de coopération avec un conteneur, lorsque la plaque-poussoir n'est plus en prise avec ledit couvercle, ledit organe de butée étant en outre adapté pour s'effacer, par l'effet de sa flexibilité, sous la poussée d'un conteneur coopérant avec ledit couvercle.

In addition, according to a preferred embodiment:

• the means for driving the cover located at the head of the line comprise a pusher plate arranged to come into engagement with said cover, and means for moving said pusher plate able to move it longitudinally along the ramp and orthogonally to the above it,
• a flexible stop member is arranged so as to prevent any sliding of a cover brought into the position of cooperation with a container, when the pusher plate is no longer in engagement with said cover, said stop member being further adapted to be erased, by the effect of its flexibility, under the thrust of a container cooperating with said cover.

• des moyens de pesée de chaque conteneur constitués d'une balance électronique, et un poste d'évacuation des conteneurs hors gabarit,
• une bande transporteuse d'évacuation des conteneurs fermés disposée de façon à prendre en charge le déplacement desdits conteneurs lorsque ceux-ci sont libérés des conformateurs,
• un poste d'étiquetage adapté pour apposer transversalement, sur le couvercle d'un conteneur fermé, une étiquette de longueur supérieure à la largeur dudit couvercle disposée de façon à dépasser de part et d'autre de ce dernier,
• des organes d'appui disposés de façon à se trouver de part et d'autre des conteneurs, associés à des moyens de déplacement vertical aptes à les déplacer le long d'un conteneur de façon qu'ils rabattent les extrémités des étiquettes, et qu'ils appliquent ces dernières sur les faces longitudinales du conteneur fermé.

Finally, the machine according to the invention advantageously includes the following equipment:

• weighing means for each container made up of an electronic balance, and a container outlet for oversized containers,
• a conveyor belt for evacuating closed containers arranged so as to support the movement of said containers when the latter are released from the conformers,
• a labeling station suitable for affixing transversely, on the lid of a closed container, a label of length greater than the width of said lid arranged so as to protrude on either side of the latter,
• support members arranged so as to be on either side of the containers, associated with vertical displacement means able to move them along a container so that they fold down the ends of the labels, and that 'they apply the latter on the longitudinal faces of the closed container.

• la figure 1 est une vue schématique en coupe longitudinale par un plan vertical axial A d'une machine conforme à l'invention,
• la figure 2 en est une coupe longitudinale par un plan horizontal axial B,
• la figure 3 en est une coupe transversale par un plan vertical C,
• la figure 4 en est une coupe transversale par un plan vertical D,
• la figure 5 en est une coupe transversale par un plan vertical E,
• la figure 6 en est une coupe transversale par un plan vertical F,
• la figure 7 en est une coupe transversale par un plan G représentant le magasin de couvercles,
• la figure 8 est une vue en perspective d'une des pièces d'un élément d'un conformateur,
• et la figure 9 en est une vue latérale partielle représentant les moyens d'entraînement des couvercles en partie basse de la rampe inclinée.

Other characteristics, purposes and Advantages of the invention will emerge from the detailed description which follows, with reference to the appended drawings which represent, by way of nonlimiting example, a preferred embodiment. On these drawings which form an integral part of this description:

• FIG. 1 is a schematic view in longitudinal section through an axial vertical plane A of a machine according to the invention,
• FIG. 2 is a longitudinal section thereof through an axial horizontal plane B,
• FIG. 3 is a cross section thereof through a vertical plane C,
• FIG. 4 is a cross section thereof through a vertical plane D,
• FIG. 5 is a cross section thereof through a vertical plane E,
• FIG. 6 is a cross section thereof through a vertical plane F,
• FIG. 7 is a cross section thereof through a plane G representing the store of covers,
• FIG. 8 is a perspective view of one of the parts of an element of a shaper,
• and Figure 9 is a partial side view showing the drive means of the covers in the lower part of the inclined ramp.

The machine shown diagrammatically in the figures is intended to ensure three operations on the trays continuously feeding this machine: a weight sorting with automatic evacuation of the trays whose weight is outside the limits set by the user, an automatic fitting of a cover, and automatic installation of an adhesive tape.

An example of a container that can be closed by means of this machine is shown in more detail in FIG. 9 and consists of a tray 1 made of a material such as semi-rigid plastic.

This tray 1 has the shape of a pyramid trunk widening upwards and has a open upper face 1a provided on its periphery with an external peripheral return 2 for latching.

The cover 3 intended to cooperate with this tray 1 is also shown in more detail in FIG. 9 and includes a peripheral snap-on rim 4 able to come over the peripheral return 2 of the tray 1 and to snap onto it. this. To this end, this rim 4 has snap-on studs such as 5 arranged towards each of the ends of the cover 3 and arranged internally at the base of the latter in order to come to bear elastically under the snap-back. 2 of tray 1.

The machine according to the invention comprises, first of all, a continuous conveying system shown in FIG. 4. This conveying system comprises a track 6 provided with an axial longitudinal slot 7, on which each tray 1 is to be manually deposited . It further comprises a chain 8 with lugs 9 driven in a closed loop around two sprockets 10, 11 with horizontal axes, said chain being arranged so that the lugs 9 protrude above the track 6 through the longitudinal slot 7.

Furthermore, interposed along this conveying system, the machine comprises means for weighing each tray 1 consisting of an electronic balance 12, and a discharge station 13 for the trays 1 out of size. These weighing means 12 and discharge 13 being of conventional type known per se will not be described in more detail.

Secondly, the machine comprises a plurality of shape conformers adapted to each surround a tray 1, coming to bear under the peripheral return 2 of the latter. These conformers consist of two elements 14, 15 each associated with drive means adapted to move them in a closed loop along which said elements are brought on either side of a tray 1 to come and surround the latter and then moved linearly so as to drive said tray, and finally caused to release the latter.

These drive means consist of two support chains 16, 17 driven in a closed loop around pinions such as 18, 19 with vertical axes. These two chains 16, 17 are also arranged so that the shapers 14, 15 surround the trays 1 when they are on track 6 of the cleat conveyor 9, downstream of the discharge station 13.

To this end, these chains 16, 17 are arranged parallel to each other, on either side of the end of the track 6, and in the extension of the latter.

These chains 16, 17 are also arranged at a height such that the elements 14, 15 of the shapers surround the trays 1 located on the track 6, substantially halfway up the latter. In this way, once these trays 1 have passed the end of the track 6, they slide down inside the conformers 14, 15, until the latter come to bear under their return from snap 2.

As indicated above, each shaper is composed of two elements 14, 15 each associated with a drive chain 16, 17. Each element 14, 15 is further divided into two parts 14a, 14b, 15a, 15b having the shape general of a conjugate L of the shape of the angles of the trays 1, said parts being arranged to come to be positioned at the right of each of the angles of said trays.

As shown in FIG. 8, each piece 14a, 14b, 15a, 15b of the shaper consists of a plate 20 pierced with two oblong holes such as 21 and provided, on one side, with a longitudinal edge 22 of conjugate shape angles of trays 1.

This plate 20 is secured to the chain 16 or 17 by means of a plate 23 on which it is fixed by means of screws 24 housed in the holes oblong 21.

The fixing of the plate 23 on the chain 16 or 17 is in turn ensured by means of two rods such as 25 projecting from said plate and locked relative to a link of said chain by means of a nut system / lock nut 26.

This plate 23 is further provided, on the underside and in the extension of the rods 25, with two fingers such as 27 arranged so as to be housed in a guide groove 28 formed longitudinally in a block 29 of plastic material disposed under the trajectory of each chain 16, 17 so as to serve as a sliding surface for each plate 23.

It should be noted that the design of the conformers makes it possible, on the one hand, to easily adjust the spacing between two elements 14, 15 thanks to the oblong holes and, on the other hand, to quickly change the conformers according to the shape of the trays 1 to be closed.

The machine further comprises, interposed along the rectilinear path of the conformers 14, 15, conforming means of shapes conjugate to that of the cross section of a cover 3. It further comprises means for feeding covers 3 adapted to present each cover at an angle to the abovementioned shaping means, in a position such that a tray 1 comes into contact with the rim 4 of this cover, the snap-back 2 of said tray being disposed at- above the snap-on studs 5 of said cover.

The shaping means comprise, first of all, and as shown in FIG. 3, a fixed coil 30 whose axis is fixed on two lateral flanges such as 31. This coil 30, on the one hand, is disposed and, d 'other hand, has flanks of shape adapted to enclose a cover 3 resting on a tray 1 so as to center the latter and to exert pressure on the flange 4 of said cover.

These conforming means include further, as shown in FIG. 6, a stirrup 32 of conjugate section of the cross section of the covers 3, intended to be moved downwards and to exert on said cover and its peripheral rim 4, a pressure capable of generating the assembly of the latching pads 5, arranged at the rear of the covers 3 relative to the direction of movement of the trays 1.

To this end, this stirrup 32 is carried by the end of the rod of a jack 33 arranged vertically, and the body of which is secured to a gantry 34 disposed above the movement circuit of the conformers 14, 15.

In addition, two vertical rods such as 35 fixed on the stirrup 32 and slidably mounted relative to the gantry 34, ensure the guidance of this stirrup.

In addition, the machine comprises, interposed between the coil 30 and the stirrup 32, a flexible support member 36 carried by a vertical plate 37 integral with the coil 30. As shown in FIG. 9, this support member , consisting of a brush 36, is arranged so as to serve as a bottom stop defining the position of a cover 3 for the purpose of driving the latter by a tray 1. In addition, this brush 36 has a flexibility suitable for that it is erased horizontally during the advance of the trays 1.

The means for supplying the covers comprise, for their part, and first of all, an inclined ramp 38 along which the covers 3 descend by gravity, and a store 39 of stacked covers disposed in the upper part of this ramp.

As shown schematically in Figure 7, the cover store has four cylinders such as 40 arranged horizontally and whose body is secured to the wall of the store 39, on the rods of which rests the stack of covers.

This store 39 further comprises four other jacks such as 41 arranged horizontally and arranged above the aforementioned jacks 40, so as to come in contact with the rim of the second cover of the stack, starting from the bottom, during their movement.

The store 39 finally comprises a jack 42 arranged orthogonally to the ramp 38 and the body of which is integral with the latter. This jack 42, placed vertically above the stack of covers 3, comprises a rod provided with a suction cup 43 adapted to allow the bottom cover to be grasped and brought to the ramp 38.

The actuation of this jack 42 is carried out once the jacks 41 have been deployed so as to come into contact with the edge of the second cover of the stack, and the jacks 40 retracted so as to allow the lower cover to descend.

The guide ramp, for its part, as shown in FIG. 4, a chute 38 supporting the covers, comprising means for lateral guidance of the said covers made up of two rods such as 44, arranged on either side of the chute .

This chute 38 is carried by a hinge pin 45 for adjusting its inclination. For example, for trays 1 as described above, the proper inclination of the ramp is 21 °.

The lateral guide rods 44 are spaced apart so as to center the covers 3 with respect to the sides of the coil 30. As shown in FIG. 9, these rods 44 extend, moreover, practically to the right of this coil 30, while the bottom of the chute 38 is interrupted at a distance from the brush 36 of low stop substantially less than the length of a cover 3.

The means for supplying the covers further comprise a retractable finger 46, such as for example constituted by the end of the rod of a jack, disposed towards the lower end of the ramp 38, and adapted to come and make protrusion above said ramp so as to stop the descent of the cover 3 located at the head of the line.

These means of supplying the covers 3 comprise, moreover, means for driving the cover 3 stopped by the retractable finger 46, capable of bringing said cover, after removal of said finger, into its low stop position against the brush 36.

These drive means comprise a first cylinder 47 disposed above the ramp 38 parallel to the latter. The body of this cylinder 47 is fixed to said ramp, so that its rod is oriented downwards.

These drive means further comprise a second cylinder 48 carried by the rod of the above-mentioned cylinder 47, so as to extend orthogonally with respect to the ramp.

Finally, they include a pusher plate 49 fixed under the core of a stirrup 50 carried by the rod of the jack 48, so as to extend parallel to the ramp 38. This pusher plate 49 also has a transverse undulation 51 intended to be positioned between two consecutive covers when this plate 49 is pressed against them.

The operation of these drive means is controlled by means for detecting the presence of a tray 1, such as for example one or more photoelectric cells.

This control and the arrangement of the drive means are capable of making them operate in the following manner.

Firstly, the retracted positions of the actuator 47 and the deployed positions of the actuator 48 are adapted to bring the plate 49 into contact with the cover 3 stopped by the retractable finger 46 and with the cover 3 located in the second position, the corrugation 51 being housed between the two covers.

On the order of the detection means, the retractable finger 46 is retracted, and the jack 47 deployed so as to bring the cover located at the head of the file to its appropriate position to be driven by a tray 1.

The jack 48 is then retracted, the retractable finger 46 having been previously deployed so as to prevent the next cover from continuing its descent. It should be noted that during the retraction of the jack 48, the cover 3 is stopped in low stop by the brush 36 and cannot therefore continue its descent.

Finally, the cylinder 47 is retracted then the cylinder 48 again deployed in order to start a new cycle.

The machine according to the invention furthermore comprises an endless conveyor belt 52 onto which the trays 1 are brought before the elements 14, 15 of the shapers move apart, thereby releasing said trays.

This conveyor belt comprises a first inclined upward section 52a, intended to raise the trays 1 so as to allow the peripheral return 2 to be released before the elements 14, 15 of conformers move away.

Finally, the machine according to the invention comprises a station for labeling closed trays 1 moving on the conveyor belt 52.

This labeling station comprises, first of all, means 53 for distributing labels of a type known per se, adapted to affix on the cover 3, a label of length greater than the width of a tray 1, disposed of so as to protrude on either side of the cover 3.

This labeling station further comprises means adapted to fold down the ends of the labels and apply them to the longitudinal faces of the closed container.

As shown in FIG. 5, these means comprise, first of all, two horizontal brushes such as 54 fixed towards the ends of the wings of a sheet 55 in the shape of an inverted U arranged above the conveyor belt 52.

This sheet 55 and these brushes 54 are arranged so that the ends of said brushes are spaced a distance less than the width of a tray 1.

These means further comprise a jack 56 arranged vertically, the body of which is fixed on a gantry 57 arranged above the conveyor belt 52, and the rod of which carries the sheet 55.

The jack 56 is slaved so as to deploy substantially before the portion of the tray covered with the label reaches its level, then to retract between two trays.

Finally, a rod 58 integral with the sheet 55 and sliding relative to the gantry 57, allows this sheet to be guided during its vertical movements.

Claims (14)

1. Machine for closing a container (1) such as a semi-rigid tray having an open side (1a), the so-called upper side, by means of a cover (3), the form of which matches that of said upper side, said container and said cover being endowed with engaging means (2, 5) so designed as to enable their assembly, whereby said machine comprises:

   - means (6-11) for continuous transportation so designed as to supply the containers (1) individually, one after the other,

   - means (38-51) for supplying covers (3), said means being so designed as to present each cover (3) in inclined manner above the upper side (1a) of a container (1) in such a position that said container comes into contact with an end face, the so-called upstream face, of said cover and drives the latter along with it,

   - forming means (30, 32) having forms matching that of the cross-section of a cover (3), so designed as to apply to said cover a pressure such as to cause the container (1) and the cover (3) to be assembled, said machine being characterised by

   - a plurality of forming devices, each composed of at least two elements (14, 15), the function of which is to cooperate so as to encompass each container (1) in the vicinity of the upper side (1a) as well as most of the perimeter of said container, and by

   - means (16-19) for driving elements (14, 15) pertaining to the forming devices and so designed as to displace the latter in a closed loop along which the elements (14, 15) of a forming device are moved towards both sides of a container (1) until they encompass the latter, whereupon they are displaced in linear manner so as to drive said container and are finally caused to release said container.
2. Machine according to Claim 1, characterised in that:

   - the means (16-19) for driving the forming devices (14, 15) are so arranged as to displace the latter along a horizontal path situated at a height so selected that said forming devices encompass the containers (1) at an intermediate level of their height,

   - the conveying means (6-11) comprise a track (6) on which the containers (1) are displaced, said track being interrupted upstream of the point at which the covers (3) are supplied so that each container (1) undergoes a downward displacement in relation to the forming device (14, 15) encompassing it, as a result of which said container is encompassed near its upper side (1a).
3. Machine according to Claim 2, characterised in that the conveying means comprise a chain (8) with drivers (9) driven in a closed loop about two gear wheels (10, 11) with horizontal axes, said chain being so arranged that the drivers (9) project above the track (6) through a longitudinal slot (7) provided in the latter.
4. Machine according to one of the preceding claims, characterised in that the means for driving the forming devices (14, 15) comprise two chains (16, 17) supporting said forming devices, said chains being driven in a closed loop about gear wheels (18, 19) with vertical axes with each chain supporting one of the elements (14, 15) of the forming devices and being arranged parallel to one another so that said elements come to cooperate with a view to driving the containers (1).
5. Machine according to Claim 4, characterised in that each element (14, 15) of a forming device is constituted by two L-shaped parts (14a, 14b, 15a, 15b) arranged opposite one another, each of said parts being carried by a supporting device (23) firmly connected to at least one link of the driving chain (16, 17).
6. Machine according to Claim 5, characterised in that:

   - the supporting device for each part (14a, 14b, 15a, 15b) of an element (14, 15) of the forming device comprises a plate (23) firmly connected to at least one link of the chain (16, 17) by means of a pin (25) and endowed with at least one finger (27) projecting from the underside,

   - a guiding track (29) arranged beneath each chain (16, 17) comprises a supporting surface so designed as to enable the plates (23) to slide, a guiding groove (28) for the fingers (27) of said plates being provided in said supporting surface.
7. Machine according to one of the preceding claims for closing a container (1) by means of a cover (3) having a peripheral engaging flange (4), characterised in that the forming means comprise a centring spool (30) with flanks so designed as to encompass the cover (3) and apply pressure to the flange (4) of the latter.
8. Machine according to Claim 7 intended for assembling the covers (3) and containers (1) endowed with engaging means (2, 5) respectively arranged at the level of the so-called upstream and downstream engaging means for said covers and containers, characterised in that:

   - the means (38-51) for supplying the covers (3) are so designed as to present them in a position such that their upstream engaging means (5) are arranged so as to correspond with the upstream engaging means (2) of the containers (1) coming into contact with said covers,

   - the conforming means comprise, downstream of the centring spool (30), a yoke (32), the cross-section of which matches the cross-section of a cover (3), and means (33) for driving said yoke along a vertical axis, said means being so designed as to displace said yoke in such a way as to cause it to apply pressure to the cover (3) at the level of the rear end of the latter with a view to bringing about assembly of the downstream engaging means.
9. Machine according to one of the preceding claims, characterised in that the means for supplying the covers (3) comprise:

   - an inclined ramp (38) endowed with lateral guiding means (44), so designed as to centre the covers (3) in relation to the flanks of the centring spool (30),

   - a magazine (39) for covers (3) stacked on top of one another, said magazine being arranged near the upper end of the ramp (38),

   - gripping means (42, 43) so designed as to grip the stacked covers (3) one by one and to deposit them on the ramp (38),

   - retractable stopping means (46) arranged near the lower end of the ramp (38), so arranged as to prevent the descent of the cover (3) at the head of the line and appearing at the level of said end,

   - and means (47-51) for driving the cover (3) stopped by the rectractable stopping means (46), said means being so designed as to supply said cover in the appropriate position so as to enable it to be driven by a container (1).
10. Machine according to Claim 9, characterised in that:

    - the means for driving the cover (3) at the head of the line comprise a push plate (49) so designed as to engage said cover and means (47, 48) for displacing said push plate, so designed as to displace it longitudinally along the ramp (38) and orthogonally above the latter,

    - a flexible stop device (36) is arranged so as to prevent any sliding of a cover (3) brought to a position in which it cooperates with a container (1) once the push plate (49) no longer engages said cover, said stop device being moreover so designed as to be pushed out of the way owing to its flexibility under the pressure of a container (1) cooperating with said cover.
11. Machine according to Claim 10, characterised in that it comprises means for detecting the position of a container (1) which are so designed as to control the means (47, 51) for driving the cover (3) which is at the head of the line.
12. Machine according to one of the preceding claims, characterised in that it comprises means (12) for weighing each container (1), said weighing means being constituted by an electronic balance and a station (13) for removing containers having dimensions which are unacceptable.
13. Machine according to one of the preceding claims, characterised in that it comprises a conveyor belt (52) for removing the closed containers (1), said conveyor belt being so arranged as to take over the displacement of said containers when the latter are released from the forming devices (14, 15).
14. Machine according to one of the preceding claims, characterised in that it comprises:

    - a labelling station (53) so designed as to affix a label transversely to the cover (3) of a closed container (1), the length of said label being greater than the width of said cover so that it juts out on either side of said cover,

    - supporting devices (54) are arranged so as to be located on either side of the containers (1), said supporting devices being associated with means (56) for vertical displacement so designed as to displace them along a container (1) so that they fold the ends of the labels over and apply the latter to the longitudinal faces of the closed container.

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