WO1994011179A1

WO1994011179A1 - Method and device for hot forming a plastic pot with a base, and resulting pot

Info

Publication number: WO1994011179A1
Application number: PCT/FR1993/001124
Authority: WO
Inventors: Claude Robe
Original assignee: France Conditionnement Automatique
Priority date: 1992-11-18
Filing date: 1993-11-17
Publication date: 1994-05-26
Also published as: FR2698037A1; FR2698037B1

Abstract

A method for producing a plastic pot with a base comprises the steps of forming a heated plastic sheet (10) with an extended forming ring (130) inserted into a cooled forming mould (200) in such a way that a free lower plastic sheet portion does not contact the inner side walls of said forming mould; creating a partial vacuum in a duct (230) provided in the forming mould and communicating with the inner side wall forming the base of the pot, in order to flatten a plastic sheet portion against said inner side wall (210') to form one surface of the pot base; delivering pressurised air onto the plastic sheet to flatten a plastic sheet portion against the inner side walls (210) of the forming mould, in particular for forming the body of the pot; withdrawing the forming ring into its retracted position; delivering pressurised air onto the still-hot free plastic sheet portion to at least partially flatten it against the cooled surface of the base and form the other pot base surface; and removing the resulting plastic pot with its base. The method is useful for producing pots with bases for containing cream-type desserts or yoghurt.

Description

Method and device for making a plastic foot cut by thermoforming, and cut thus obtained.

The present invention relates generally to the field of the automatic manufacture of plastic foot cups for the packaging, in particular of food materials such as dessert creams or even yogurts, and more particularly a new process for producing such cuts as well as an implementation implementation device.

The invention also relates to a new type of plastic foot cutter.

There is already known a process for the industrial manufacture of foot cups by molding, which mainly consists in injecting thermoplastic materials in the liquid state into individual molds having the shape of the desired foot cup, and in demolding the preformed foot cups. obtained after a cooling phase.

This type of process has several drawbacks, however.

First of all, according to this process, pots or individual foot cups are necessarily made which require, with a view to grouping them by two, four, six or more, the use of cartons or grouping caps. These boxes or grouping caps having particular and complex shapes, require an expensive implementation which increases the cost of production of the products packaged in these foot cuts. In addition, the establishment of these grouping caps on the foot cups produced adds an additional step in the overall manufacturing process, and conditions such products, which also increases their cost of production.

In addition, by using this method of manufacturing foot cups, it is known that the place of manufacture is then almost always different from that of filling and sealing of the foot cups or preformed pots. It is therefore easy to understand that the transport and routing constraints of these preformed pots or cups to the filling and sealing stations considerably increase the production costs of this type of product, especially if we consider that all of the operations must be carried out under conditions of perfect sterility. We then need a large workforce. In order to overcome the aforementioned drawbacks of this type of manufacturing process by molding, techniques have been developed for manufacturing pots, cups or containers for yogurts or milky creams which are techniques for thermoforming sheets of polystyrene, polypropylene or the like, these techniques can then be carried out directly before the filling and sealing stations of said pots.

In particular, documents GB-A-2 079 668 and GB-A-926 359 disclose processes for producing a foot cut by thermoforming, according to which a plastic film is hot stamped by a forming punch for introduce it into a forming mold, then the bottom of the mold is moved vertically by screwing so as to form the bottom and the base of the cut. In addition, according to a variant of the method taught by the document GB-A-926 359, the bottom and the base of the cup are formed by blowing air onto the stamped plastic film.

These known thermoforming methods and devices are complex and costly to implement. In addition, they only allow to obtain pots of very stripped shape. In particular, the method described in document GB-A-926 359 can only produce pots with a straight foot.

? Ω '> a

Document US-A-695 23 also discloses a process for producing by thermoforming a straight plastic foot cup, whereby the cup obtained has interior recesses due to the thermoformed foot. These recesses are inaccessible places for a consumer and yet fill with product during filling

9 5 'of such a cut. These corners therefore represent spaces lost to production.

The present invention aims to propose a new thermoforming process for producing plastic foot cups, which makes it possible to obtain foot cups having inter alia a foot of flared or conical shape and a smooth, continuous and which does not have inaccessible spaces likely to fill with consumable material. In addition, the invention provides a new device for implementing this method, which is a simple device and an apparatus.

5 which allows inter alia to manufacture according to the method according to the invention, a plurality of foot cuts simultaneously, these cuts being automatically assembled and not requiring the use of cartons or grouping caps.

More particularly, the production method according to the invention comprises the steps consisting in: a) stamping a heated plastic film, by means of a forming punch provided at its lower end with a drawing crown in the extended position so as to introduce it into a mold

Forming machine having cooled inner side walls, while leaving a lower part of the plastic film free from any contact with the inner side walls of said forming mold, the forming punch being in the low position inside the forming mold , with the stamping crown protruding holding the plastic film inside said forming mold: b) creating a depression in a duct provided in the forming mold and communicating with the inner side wall forming the cutting foot, so as to press a part of the plastic film on said inner side wall to form one of the faces of the foot of

"cut affecting the shape of the latter, c) injecting pressurized air onto the plastic film so as to press a part of the plastic film against the internal lateral walls of the forming mold to form in particular the body of the cut,

²⁵ d) retracting the stamping ring such that it is in the retracted position inside the forming punch held down inside the forming mold, e) while preferably maintaining depression in said conduit in the forming mold, inject air under pressure on the part

- ³⁰ still free of the plastic film so as to press at least a portion against the cooled face of the foot and form the other side of the heat-sealed cutting foot to said cooled face, f) unmolding the plastic foot cut obtained . According to another characteristic of the method according to the invention, in step c) the pressure of the air injected onto the stamped plastic film is between approximately 1.105 Pa and 3.105 Pa; in addition, in step e) the injected air pressure is between approximately 1.105 Pa and 3.105 Pa.

In addition, according to the invention, the device for implementing the method according to the present invention comprises two parts, a counter-mold and a forming mold, capable of moving vertically relative to each other. to come against each other and pinch the plastic film positioned therebetween, the counter-mold comprising a frame which comes to pinch the plastic film as well as a forming punch placed inside the ^{^} armature and adapted to move verticale¬ lies so as to be introduced into the forming mold through an opening in the frame, the forming punch having at one of its ends a movable swaging ring adapted to come into projection of said punch so as to deform the heated plastic film to introduce it into the forming mold when said forming punch moves vertically in the direction of the latter, the forming mold having inner side walls s which have essentially the shape of those of a foot cup, at least one lateral duct placed towards the outside adjacent to said interior side walls communicating with the outside, and in which cold water circulates so as to cool the internal side walls of said mold, at least one duct communicating on the one hand with a part of the internal side wall forming the cutting foot, and on the other hand with the outside, in which a depression is created to press a part of the plastic film on said inner side wall forming the cutting foot, and a conduit which opens into the part of the cutting foot of the forming mold and into which pressurized air is injected to form the cutting foot.

The description which follows with reference to the appended drawings, given by way of nonlimiting examples, will make it clear what the invention consists of and how it can be implemented. Figures 1 to 8 show, in vertical section, a first embodiment of the thermoforming device according to the invention, at the various stages of the process for producing a foot cut according to the invention.

Figures 9 to 13 show, in vertical section, a second embodiment of the device according to the invention, at the various stages of the thermoforming process according to the invention.

FIG. 1 represents an embodiment of a foot cut according to the invention.

FIG. 15 represents a set of foot cuts obtained by means of the method according to the invention.

As a preliminary, it will be noted that from one figure to another, identical or similar elements or parts have been designated as far as possible by the same reference signs, and will not be described in

15 each time.

Referring first to Figure 1, there is shown a device for implementing a method for producing a plastic foot cut by thermoforming a film of thermoplastic material such as polystyrene or polypropylene. The different stages of

20 process will be explained later. This device has two parts, an upper part called counter mold 100 and a lower part called forming mold 200. These two parts are able to move along a vertical axis XX 'relative to each other to come l 'against one another and pinch the plastic film 10 positioned ^~ ^ ^~ - between them.

Against the mold 100 comprises a frame 1 10 of essentially cylindrical shape positioned along the vertical axis XX 'of relative movement of the counter mold and the forming mold. This cylindrical shell 1 10 includes an interior conduit 12 January ^™ essentially cylindrical in extending along the axis XX 'and which includes an opening or port 1 greater than 13, which has a much smaller section than that of the duct 112 and a lower opening 1 11 which has the size of the section of the pipe 1 12. Inside this pipe 1 12 is positioned a forming punch 120 which comprises a handle 1 20a mounted to slide in a passage 1 14 provided in the upper part of the frame 1 10, adjacent to the orifice 1 13. Thus, this forming punch 120 is able to move vertically with respect to the frame 1 10 in the duct 1 12 and towards the outside of said duct via the lower opening 1 1 1, using a jack placed outside the frame and which n is not shown in Figure 1. In addition, the forming punch 120 has at its lower end 121 a drawing crown 130 which comprises a base 1 30a connected to a cylinder 131 placed inside the body 1 20b of the forming punch 120 and controlled from outside the frame 1 10, so that said drawing ring 130 is able to move vertically relative to forming punch 120 in order to occupy two positions:

an extended position in which the stamping crown 130 projects from the punch at its lower end 121,

a retracted position in which the drawing crown 1 30 is placed inside a housing 122 provided in the forming punch 120.

It should be noted that the external actuator for controlling the forming punch 120 and the internal actuator 131 are independent.

In addition, the forming punch 120 has two internal vertical conduits 123, 124, which extend in parallel in the handle 120a of the forming punch, the first vertical conduit 123 emerging inside the housing of the body of the punch containing the inner cylinder 1 31 and the second vertical conduit 124 opening into the housing 1 22 containing the drawing crown 131. These two vertical conduits 123,124 respectively have two upper openings position¬ born in the handle 120a of said punch outside the frame 1 10. The first vertical duct 123 allows injection and evacuation of pressurized air for actuation of the internal cylinder 131 which controls the movement of the drawing crown 1 30. The second vertical duct 124 is intended, as will be explained in more detail later, to evacuate from above the air injected under pressure into the lower part of the forming mold by the 'through a conduit provided for this purpose. Furthermore, the body 120b of the forming punch 1 20 has a lateral opening 125 which forms a communication conduit between the conduit 1 12 of the frame 1 10 and the housing containing the internal cylinder 131 in order to evacuate, the if necessary, the air injected into the conduit 123 towards the jack 131.

It should be noted that the inner duct 1 12 here having a larger section than the section of the body of the forming punch 120, there remains a space between said punch and the inner side walls of the frame 1 10. As we will see subsequently, this space makes it possible to form an air passage duct from the counter-mold 100 to the forming mold 200 when they are placed one against the other.

The forming mold 200 has an inner part open upwards facing the lower opening 1 1 1 of the frame 1 10 of the counter mold 100. This inner part essentially has the

15 in the form of a foot cup. More particularly, the forming mold has internal side walls 210, 210 'which essentially have the shape of the walls of the foot cut. The forming mold 200 has an upper side wall 210 forming the body of the cup, which has a surface that is substantially convex inward.

20 of said mold, symmetrical in revolution about the axis XX ′. It also has a lower side wall 210 ′ forming the base of the cup which has a surface symmetrical with respect to the axis XX ′ of essentially frustoconical shape. In addition, the frustoconical lower wall extends towards the bottom of the mold from a horizontal plate 210 "intended to receive, as described later, a part of the film to form the bottom of the foot cut. upper and lower side walls 210, 210 ′ are separated, the lower side wall 210 ′ being located in the center and at the bottom of the mold. The upper opening of the forming mold 200 corresponds to the lower opening 1 1 1 of the counter mold 100. in

The forming mold 200 comprises an air blowing duct 240 which has two lateral air inlets and which opens laterally inside the forming mold opposite the lower side wall 210 'placed in the center and at the bottom of the mold. This conduit 240 is intended for

35 receive pressurized air to form the foot of the cup. On the other hand, the forming mold 200 comprises a lateral duct 220 which has an inlet and an outlet placed symmetrically opposite with respect to the axis XX ¹ of relative movement of the counter mold 100 and the forming mold 200. This lateral duct 220 is positioned outside the inner part of the forming mold adjacent to said upper side wall 210. Cold water circulates in this lateral duct 220 so as to cool the upper lateral inner wall 210 of the mold of forming 200. In addition, the forming mold comprises a conduit 230 which is located below said horizontal plate 210 "and opens on the one hand towards the interior of the forming mold by small lateral conduits directly on the lower side wall 210 'and on the other hand towards the outside of the mold by a lateral opening by which a vacuum is created inside said conduit 230 to press a part of the plastic film ur said frustoconical lower side wall 210 'thus forming the cutting foot.

According to an alternative embodiment shown in Figures 9 to 1 3, the conduit 1 12 of the counter mold 100 has in a high part a section substantially equal to that of the forming punch 120 so that the latter slides in leaktight manner. the interior of said conduit 1 12. The seal between the punch and the counter-mold is ensured by a seal 150 placed in the internal wall of the frame 1 10. In the lower part, the conduit 1 12 has a cross section greater than that of the forming punch 120, this section corresponding substantially to the opening of the forming mold 200. The lower part of the duct 1 12 opens outwards via a lateral duct open on the orifice 1 13. The space defined between the punch 120 and the internal walls of the frame 1 10 makes it possible to form an air passage duct from the counter-mold 100 to the forming mold 200 when they are placed one against the other.

In addition, the forming punch 120 has at its lower end 121 a water cooling circuit 140. According to the embodiment shown, the stamping crown 1 30 comprises a base 1 30a secured to a rod 1 30b actuated by an external jack here not shown so that it slides vertically inside the punch 1 20 to bring the crown 1 30 in the two positions described previously. According to the embodiment shown, the rod 1 30b and the crown 1 30 form a single piece.

As can be seen in FIG. 9, the forming punch no longer comprises a vertical duct 123, but still includes the duct 124 for the evacuation of air during the blowing of air for the formation of the base of the cup as this will be described in more detail later.

The forming mold 200 here has removable parts in translation 250 forming the part corresponding to the cutting foot. These removable parts 250 symmetrical with respect to the axis XX ′ move in translation between a separated position and a close position. In the close position, the union of the interior walls of said removable parts 250 forms the bottom wall 210 'of the forming mold. This lower wall 210 'symmetrical in revolution about the axis X-X' has a first part which converges towards the inside of the mold and a second part flared downwards connected together to form a substantially bent surface. The position of the conduits 240 and 230 is more or less reversed with respect to the embodiment of FIG. 1. The air blowing conduit 240 is located below the cutting foot part. It opens laterally outward and inward of the cutting foot through a central opening on a flat diffuser 260. The suction duct 230 has a circular opening surrounding the diffuser 260 which communicates with a lower interior part of the mold. forming adjacent to the side wall 210 'forming the base of the cut and an opening to the outside through which a depression is created to press the film on said wall 2 10'.

The two embodiments shown in FIGS. 1 to 1 3 then make it possible to form a cutting foot of flared shape downwards, and more particularly a foot of conical shape.

With reference to FIGS. 1 to 8, we will now describe the process for producing foot cuts according to the invention.

In a preliminary step shown in Figure 1, positioning a plastic film 10 against the frame 1 10 of the counter mold 100 so that it obstructs the lower opening 1 1 1. The two parts of the mold are then separated. The forming mold 200 then moves vertically upwards relative to the counter mold 100 which remains fixed, to come against the counter mold, so that the plastic film 10 is pinched between the frame 1 1 0 and the outer edges of the forming mold 200. The plastic film 10 then comprises a part which is positioned exactly at the joint of the lower opening 1 1 1 and the upper opening of the forming mold 200. The entire device is brought to about 140 degrees, therefore when the plastic film 10 is pinched between the forming mold and the frame 1 10 of the counter mold, it is itself carried by conduction at a temperature of about 140 degrees.

As shown more particularly in FIG. 2, a certain quantity of cold water circulates permanently in the conduit 220 so as to permanently cool the inner side wall 210 of the forming mold. In a subsequent step, is injected pressurized air at about 6.10- ⁵ P _a in the duct 123 of the forming die so as to compress the spring of the actuator 131 which acts on the pressing ring 230 for celle- it comes in the extended position. Simultaneously, under the action of the external jack, not shown, the forming punch 120 descends so that it enters the inside of the forming mold 200 via the opening 1 1 1 and stamps via the stamping crown 130 the plastic film 10 heated to introduce it into the forming mold 200.

As shown more particularly in FIG. 3, when the forming punch 120 is in the low position the drawing crown 130 has introduced the plastic film 10 inside the forming mold 200 so that it places a part of said film 10 against the horizontal plate 210 "of the forming mold thus forming the bottom of the foot cut. A lower part of the film remains free from any contact with the internal lateral walls of the forming mold. This free lower part located to the right of the interior opening of the conduit 240. Simultaneously a depression is created in the conduit 230 provided for this purpose in the forming mold 200 and communicating with the interior lateral wall 210 ′ forming the cutting foot so as to press a part of film on said inner side portion 210 'to form the outer face of the cutting foot, which cools in contact with said side wall 210', affecting the shape of the cutting foot.

In a subsequent step, as best shown in FIG. 4, the stamping crown 130 being maintained in the extended position and the forming punch 120 in the low position, the upper hole 1 13 of the frame 1 10 is injected the air under pressure at 2.10 ^ Pa and in this way air is blown via the duct 1 12 on the part of the film 10 introduced into the forming mold 200 at the level of the body of the cut

10 so as to press said film against the inner side wall 210 of the forming mold 200 forming said cutting body. This inner side wall 210 being cooled, this part of the plastic film is thus cooled so that it takes the shape of said wall. The entire plastic film is pressed and cooled against the interior side walls ι ς

210,210 'forming the cut so as to form the plastic cut. As shown in FIG. 5, once the plastic film 10 has sufficiently cooled, the injection of pressurized air at 2.10 ^ Pa into the duct 1 12 is stopped from above, as well as the pressurized air at 6.10 ^ Pa in the conduit 123 in such a way that the jack 131 rises by relaxing the spring and reposition the drawing crown 130 in the retracted position in the housing 122 of the forming punch 120 so as to leave free the part of the film pressed against the inner side wall 210 'forming an outer face of the cutting foot.

In a subsequent step, as shown in FIG. 6, while maintaining the vacuum inside the pipe 230 and the circulation of cold water in the pipe 220, air is injected under pressure at about 2.10-5 Pa inside the duct 240 so as to blow air under pressure on the part of the free plastic film still hot inside the mold. In this way, it is pressed against the face of the cooled cutting foot to form another face of the heat-sealed cutting foot on said first face. It should be noted that the air blown through the conduit 240 escapes to the outside by circulating in the conduit 124 provided in the forming punch 120. This avoids overpressures on the plastic film inside the mold that can cause tearing of it. This face of the cutting foot cools on contact with the first cooled external face. As a result, as shown in FIGS. 7 and 8, the forming punch 120 is raised inside the duct 1 12 of the frame 1 10 and when the cooling is sufficient, the forming mold descends to its initial position. so as to unmold the plastic foot cup thus obtained.

With reference to FIGS. 9 to 13, we will now describe the method according to the invention by means of an alternative embodiment of the device of FIGS. 1 to 8.

First of all, in a preliminary step, the removable parts 250 of the forming mold approach each other by translation from an initial position separated to form the part of the mold corresponding to the cutting foot. The plastic film 10 is then positioned between the counter-mold 100 and the forming mold 200 which come together to pinch the heated plastic film 10. The forming punch 120 descends with the drawing crown 130 projecting from its lower end 121 so as to stamp the heated plastic film 10 in order to introduce it into the forming mold 200.

As best shown in FIG. 10, when the forming punch is in the low position the drawing crown 130 maintains on the one hand a part of the plastic film free from any contact with the internal lateral walls 210, 210 ′ of the forming mold, and on the other hand, a part of the film which extends horizontally between the edges of the drawing crown pressed against the diffuser 260.

In a subsequent step shown in Figure 1 1, air is blown under pressure inside the forming mold via the conduit 1 12 of the counter mold so as to press the film against the inner side wall 210 forming the body of the cup. In addition, a depression is created in the conduit 230 which communicates with the flared part of the bottom wall 210 'of the forming mold so that the film comes to press against said flared part down 210' forming the cutting foot. Then, as shown in FIG. 12, the drawing crown 130 retracts inside the housing 122 of the forming punch 120 and while maintaining the vacuum in the conduit 230, as well as the pressurized air at the inside the forming mold via line 1 12, pressurized air is injected through line 240 into the forming mold 200 of so as to press the part of the film still hot pressed on the diffuser on the one hand against the flat surface obtained at the end cooled by the cooling circuit 140 of the punch 1 20 when the stamping crown 1 30 is positioned at the inside the housing 1 22 and on the other hand against the cooled internal face of the cutting foot. This forms the bottom of the cut and an outer face of the heat-sealed cutting foot to the inner face. Similarly, the injected pressurized air escapes through the conduit 124 to the outside. Finally, as can be seen in Figure 13, when the film is completely cooled, the plastic cup obtained is removed from the mold. The removable parts 250 of the forming mold move apart in translation in the opposite direction in order to return to their initial position and the punch goes back up inside the frame. The removable parts allow the molds to be removed from the mold which have feet with a more complex flared shape, without risk of incidents during demolding.

FIG. 14 shows an example of a foot cut with a foot 320 of conical or flared shape having a body 310 with a flange 31 5. It should be noted that the foot 320 has a bulk which is always less than the lateral dimensions of the body of the cup 310. This foot is here fluted vertically on both sides. In addition, the interior of the foot cut obtained has a smooth and continuous surface from the top to the bottom.

According to the invention, it is possible to produce a device (not shown) allowing the simultaneous manufacture of several foot cuts. This device then comprises several devices as described above positioned in parallel and which act simultaneously on the same plastic film 10 positioned between the two parts of each of said devices. In addition, this apparatus comprises means for producing a cutting line of lower resistance between each foot cut made. This gives, as shown more particularly in FIG. 1 5, a set of four, six or eight assembled foot cuts, with between each of the foot cuts lines of lower resistance which allow manual and easy cutting of the foot cuts. way to consume them individually.

Claims

1. A method of making a plastic foot cut, characterized in that it comprises the steps consisting in: a) stamping a heated plastic film (10), by means of a forming punch (1 20) provided at its lower end (121) with a drawing crown (130) in the extended position so as to introduce it into a forming mold (200) having interior side walls (210, 210 ′) cooled, while leaving a lower part of the plastic film (10) free from any contact with the internal lateral walls (210, 210 ') of said forming mold (200), the forming punch (120) being in the low position inside the mold forming (200), with the drawing crown (130) projecting keeping the plastic film (10) inside said forming mold (200): b) creating a depression in a duct (230) provided in the mold forming (200) and communicating with the inner side wall e (210 ') forming the cutting foot, so as to press a part of the plastic film on said inner side wall (210') to form one of the faces of the cutting foot affecting the shape of the latter, c) injecting pressurized air on the plastic film so as to press a part of the plastic film against the internal side walls (210) of the forming mold (200) in particular to form the body of the cut, d) retract the crown stamping (130) so that it is in the retracted position inside the forming punch (120) held in the low position inside the forming mold (200), e) while preferably maintaining the vacuum in said conduit (230) in the forming mold (200), inject air under pressure on the free part still hot of the plastic film (10) so as to press at least a part against the cooled face of the foot and form the other side of the heat-sealed cutting foot at said fac e cooled, f) unmold the plastic foot cut obtained.

2. Production method according to claim 1, characterized in that in step c), the pressure of the air injected onto the pressed plastic film is between approximately 1.10-5 Pa and 3.10 ^ Pa.

3. Production method according to one of claims 1 or 2, characterized in that in step c), the air injected under pressure also makes it possible to position a part of the plastic film (10) heated against at least one part of the inner side wall (210 ') forming the base of the cut of the forming mold (200).

4. Production method according to any one of claims 1

10 to 3, characterized in that steps c) and d) are carried out before step b).

5. Production method according to any one of claims 1 to 4, characterized in that it comprises an additional step preliminary to step a), during which removable parts (250) of the forming mold (200 ) approach each other by translation from a

- - initial position apart, to form the part of said mold (200) corresponding to the base of the cut.

6. Production method according to claim 5, characterized in that in step f) the removable parts (250) move away from one another by translation from the close position towards the separated position.

20 7. Production method according to any one of claims 1 to 6, characterized in that in step a), the drawing ring (1 30) positions part of the plastic film (10) heated against a part of the interior side walls (210 ') forming the base of the cut of the forming mold (200). 5

8. Production method according to any one of claims 1 to 7, characterized in that the free part of the plastic film (10) corresponds to a side part which extends essentially in a downward extension of the inner side wall ( 210) forming the cup body of the forming mold (200). 0

9. Production method according to any one of claims 1 to 8, characterized in that in step e) the air pressure injected is between approximately 1.10 ⁵ Pa and 3.105 p _a .

5

10. Device for implementing the production method according to one of claims 1 to 9, characterized in that it comprises two parts, a counter-mold (100) and a forming mold (200), capable of move vertically with respect to each other to come against one another and pinch the plastic film (10) positioned between them, the counter-mold (100) comprising a frame (1 10) which pinches the plastic film (10) as well as a forming punch (120) placed inside the frame (1 10) and able to move vertically so as to be introduced into the forming mold ( 200) via an opening (1 1 1) provided in the frame (1 10), the forming punch (120) comprising at one of its ends (121) a movable drawing crown (130) capable of projecting said punch (120) so as to deform the heated plastic film (10) to introduce it into the forming mold (200) when said punch forming (120) moves vertically in the direction of the latter, the forming mold (200) comprising internal lateral walls (210) which essentially have the shape of those of a foot cut, at least one lateral duct (220) placed outwardly adjacent to said interior side walls (210) communicating with the exterior, and in which cold water circulates so as to cool the interior side walls (210) of said mold (200), at least one conduit ( 230) communicating on the one hand with a part of the inner side wall (210 ′) forming the cutting foot, and on the other hand with the outside, in which a depression is created to press a part of the plastic film on said inner side wall (210 ') forming the cutting foot, and a conduit (240) which opens into the part of the foot of the forming mold (200) and into which air is injected under pressure to form the foot of the chopped off.

1 1. Device according to claim 10, characterized in that there is provided a space (1 12) between the frame (1 10) and the forming punch (120), this space (1 12) communicating with the opening (1 1 1) and an orifice (1 13) opening to the outside provided in said frame (1 10) in order to form a passage conduit from the counter-mold (100) to the forming mold (200) when they are one against the other, into which one can inject via the orifice (1 13) pressurized air to press the plastic film (10) stamped by the stamping crown (130), on the inner side walls (210) of the forming mold (200).

12. Device according to one of claims 10 or 1 1, characterized in that the stamping ring (130) is adapted to move vertically relative to the forming punch (120) by means of a control placed inside said punch, so as to occupy two positions:

an extended position in which the stamping crown (130) projects from said punch at one of its ends (121),

- A retracted position in which the stamping ring (130) is placed inside a housing (122) provided in the forming punch (120).

10 13. Device according to one of claims 10 to 12, characterized in that the forming punch (120) is slidably mounted on the frame (1 10), and in that its vertical movement is controlled by an external cylinder independent of the internal control (131) of the stamping ring (130).

^{1 51 5}

14. Device according to one of claims 10 to 13, characterized in that the counter-mold (100) is the upper part of the device, and the forming mold (200) is the lower part.

15. Device according to one of claims 10 to 14, characterized in that the forming mold (200) comprises removable parts (250) in translation corresponding to the part of the mold (200) forming the base of the cut.

16. Apparatus for manufacturing a plurality of plastic foot cups, characterized in that it comprises a plurality of devices according to one of claims 10 to 15, which operate

⁵ simultaneously on a single plastic film positioned in said devices, and in that it comprises means for producing a cutting line of lower resistance between each foot cut made.

17. Foot cup (300) made of plastic material according to the method according to claims 1 to 9, characterized in that it comprises

³⁰ a main part (310), the base of which extends downwards by a foot (320), the foot (320) having two thermally welded facing faces and the main part (310) having a smooth and continuous internal surface.

18. Foot cup (300) according to claim 17, characterized in that its foot (320) has a flared shape downwards.

^ 19. Foot cutter (300) according to one of claims 17 to 18, characterized in that the two faces of the foot (320) are grooved vertically.