INSTALLATION AND PROCESS FOR MANUFACTURING A FOOD POT

Abstract

The invention relates to a method for manufacturing a food container and a corresponding installation, the method comprising the steps of: placing a strip of paper (10) in a mold having a base and a side wall, opposite the side wall (6); applying a jet of compressed air (42) between the paper strip (10) and the side wall; and then thermoforming a sheet of plastic material in the mold. Abstract figure: Figure 3

Description

Title of the invention: INSTALLATION AND METHOD FOR MANUFACTURING A FOOD JAR Technical field

[0001] The present disclosure relates to the field of food containers and their manufacture and in particular food pots which can contain liquid or semi-liquid products such as yogurt, milk, or equivalent. Prior art

[0002] The manufacturing process generally used to manufacture food pots consists of shaping a sheet of plastic material (usually polystyrene) by a thermoforming process. Several dozen pots are thus formed in one operation. A banner presenting the relevant commercial and regulatory information is placed in the mold before thermoforming. This banner has one side provided with a hot-melt glue which adheres to the plastic sheet during thermoforming. After thermoforming, the pots are filled and sealed with a film. Finally, the pots are cut to obtain a group of pots in the desired number, ready for packaging.

[0003] Incorrect positioning of the banner leads to a deterioration in the aesthetic quality of the pot: the banner may be positioned obliquely, it may have a wavy appearance or it may have defects in adhesion to the pot. In extreme cases, the integrity of the contents may be threatened and the pot will be discarded.

[0004] There is therefore a need to improve control of the positioning of the banner in the mold. Summary

[0005] The present disclosure meets this need.

[0006] A method of manufacturing a food pot is provided comprising the steps of: placing, in a mold having a bottom and a side wall, a paper band opposite the side wall; applying a jet of compressed air between the paper band and the side wall; then thermoforming a sheet of plastic material in the mold.

[0007] It is thus possible, by the Venturi effect, to ensure that the banner is pressed against the side wall of the mold: the Venturi effect is created by the jet of compressed air and it only disappears once the banner is pressed against the side wall. Consequently, positioning defects of the banner in the mold are minimized and the final product is made to conform to aesthetic and health expectations.

[0008] According to one embodiment, after the “arrange” step, a crescent-shaped gap is formed between the banner and the side wall of the mold, the compressed air jet being applied in a middle zone of the crescent.

[0009] The band is longer than the perimeter of the mold cavity. Thus, once rolled up on itself, one of the ends of the band, radially internal, touches an internal surface of the band. A portion of the band is pushed radially outward against the side wall. However, a detachment point characterizes the place where the band detaches from the side wall. Between the internal end and the detachment point, a spacing of substantially crescent moon shape is formed with the side wall.

[0010] It is understood that the term "crescent moon" is to be understood in the broad sense since, when the side wall is not strictly cylindrical (for example when it is square), the radially outer side of the crescent moon does not strictly describe an arc of a circle.

[0011] According to one embodiment, the compressed air jet is oriented substantially parallel to the side wall of the mold. In this orientation, the Venturi effect is maximized for a given air flow.

[0012] According to one embodiment, the method comprises, before applying the compressed air jet, a step of positioning a removable compressed air blowing nozzle in an operating position. Using a removable nozzle makes it possible to position the air jet at an optimal location without worrying about the precise position of the banner in the mold (and in particular its ends). Also, the nozzle can be removed to a rest position after blowing air and before the thermoforming step. This makes it possible to adapt the air blowing system to existing installations: conversely, when the nozzle is fixed, it may be necessary to modify the thermoforming die to avoid mechanical interference between the nozzle and the die.

[0013] According to one embodiment, the pressure of the compressed air jet is between 0.5 and 6 bar. This value range is an ideal compromise: 0.5 bar is sufficient to generate a Venturi effect but above 6 bar, the banner risks being damaged, getting stuck in an inappropriate position in the mold, or even coming out of the mold.

[0014] The pressure may be constant during the operation of pressing the banner against the side wall of the mold. This pressure may be chosen according to the expected or detected gap between the banner and the side wall of the mold. Alternatively, the pressure may vary according to a given variation law: for example, the pressure may be high at the start of the pressing operation and then it may decrease. Indeed, while the distance between the banner and the side wall decreases, less pressure is necessary to maintain the Venturi effect.

[0015] According to one embodiment, the compressed air jet is applied for a duration of between 0.3 and 2 seconds. The duration of application of the air jet can be predefined based on an estimate of the time required to press the banner against the side wall, for a given banner and a given mold. Alternatively, the duration can be adjusted dynamically, in connection with a banner gap detector: once the banner is pressed against the side wall, the compressed air jet can be interrupted. The detector can be an optical detector in particular.

[0016] The invention also relates to a food pot manufacturing installation configured to implement the method according to one of the embodiments mentioned above, the installation comprising: a mold having a bottom and a side wall; compressed air blowing means capable of applying a jet of compressed air between a paper band arranged in the mold and the side wall; and thermoforming means.

[0017] According to one embodiment, the compressed air blowing means comprise a removable nozzle which can be moved by actuators between a rest position and an operating position.

[0018] According to one embodiment, the installation comprises a detector identifying the position of a gap between the banner and the side wall of the mold drawing a crescent moon, the operating position being a middle position of the crescent moon.

[0019] The detector may be an optical sensor which makes it possible, in a given frame of reference, to locate the crescent moon (angular extent and radial width) in order to determine its median position (for example in a cylindrical frame of reference) at which the nozzle will be placed to blow air.

[0020] According to one embodiment, the compressed air blowing means comprise an orifice arranged in the bottom of the mold, from which orifice the compressed air jet is formed. Thus, as an alternative or in addition to the nozzle, a jet of air can be blown through the bottom of the mold. The orifice can be in the vicinity of the side wall. In a variant, the bottom has a plurality of orifices: they will either be simultaneously activated to blow air, or, if a detector is provided to locate the crescent moon, only one or some orifices located in the crescent moon will be activated.

[0021] The various aspects of the invention thus make it possible to firmly press the banner against the side wall of the mold and thus obtain better control over the positioning of the banner in the mold. The final product is therefore aesthetically and hygienically compliant with expectations. Brief description of the drawings

[0022] Other characteristics, details and advantages will appear on reading the detailed description below, and on analyzing the attached drawings, in which:

[0023] [Fig. 1] describes a method of manufacturing a food jar.

[0024] [Fig.2] shows a defect observed in the positioning of a banner in the mold.

[0025] [Fig.3] represents an installation according to the invention making it possible to carry out the method according to the invention.

[0026] [Fig.4] illustrates a variant of [Fig.3]. Description of the embodiments

[0027] [Fig.l] summarizes very schematically three stages (a, b, c) in the manufacture of a food jar.

[0028] In a first step (a), a sheet 1 of plastic material is placed on a mold 2, the sheet 1 resting on a support surface 3 of the mold 2. The sheet 1 is generally made of polystyrene and has a thickness of between 0.80 and 1.20 mm. It can be thinner.

[0029] The mold 2 has a series of recesses 4, only one of which is visible in [Fig.l]. The recess 4 is delimited by a lateral surface 6 and a bottom 8. The example illustrated shows a recess with an inclined side wall. The general shape of the recess 4 may be truncated or of square section.

[0030] A banner 10 or strip of paper, that is to say a sheet longer than it is wide, and containing commercial and / or regulatory information is placed in the recess 4 of the mold 2, surrounded on itself to form a sleeve in which the plastic will be thermoformed.

[0031] A thermoforming step (b) is then carried out, by applying a vertical force using a punch 12. The sheet 1 is thus deformed to match the shape of the mold 2. The punch 12 moves to a given position, for example a position in which the sheet 11 comes into contact with the bottom 8 of the recess 4.

[0032] After thermoforming (b), the deformed sheet 11 is filled with the liquid or semi-liquid product, cut and closed to obtain a pot 21 as shown in [Fig.l] (c). The pot 21 comprises a collar 22 on which a cover 23 is sealed. An internal cavity 24 containing the liquid or semi-liquid product is delimited by a side wall 26 and a bottom 28.

[0033] The banner 10 may be bonded by an adhesive layer 30 around the outer face of the side wall 26. The adhesive layer 30 may be a hot-melt film applied to the inner surface of the banner.

[0034] [Fig.2] shows the position of the banner 10 in the mold in an isometric view and in a top view.

[0035] For simplification, the mold section is represented as a circle, with center O. The principles discussed below are naturally applicable to any type of mold section.

[0036] It is observed that the banner 10 takes a natural position of mechanical equilibrium once placed in the mold. An arc of a circle going from one end A to a point C is pressed against the side wall 6. The point C is a detachment point, that is to say a point from which the banner 10 moves away from the side wall 6. The arc of a circle going from C to B, second end, is thus at a distance from the side wall 6. The end B is in contact with the internal surface 10.1 of the banner 10.

[0037] The zone marked E materializes a spacing zone between the banner 10 and the side wall 6. The distance marked “e” corresponds, in this spacing, to the greatest distance between the banner 10 and the side wall 6.

[0038] The angle (noted a) results from a mechanical balance and can be between 30 and 180° depending on the size of the mold, and the length and thickness of the banner. The coefficient of friction of the banner on itself or on the side wall, as well as the shape of the mold can also affect the shape of the spacing E. Often, the spacing E can describe a crescent moon profile L.

[0039] According to the invention, a jet of compressed air is directed into the gap between the banner 10 and the side wall 6 to reposition the banner against the wall by a Venturi effect.

[0040] The compressed air jet can be applied at a midpoint D of the crescent moon L. Point D can be located on the bisector of angle a equidistant from wall 6 and banner 10. Since a compressed air jet is not one-dimensional, it will be understood that applying an air jet to point D means that the air jet is centered on point D.

[0041] [Fig. 3] schematically illustrates an installation for implementing the blowing method: a nozzle 40 can project a jet of compressed air 42. The jet of compressed air 42 can flow parallel to the side wall 6. The nozzle can be perpendicular to the support surface 3 of the mold. The outlet section of the nozzle 40 can be circular. Alternatively, the nozzle 40 can have a rectangular section (a groove), oblong or describing an arc of a circle, in order to blow a more diffuse jet of air into the space between the banner 10 and the side wall 6 of the mold.

[0042] The nozzle 40 may be fixed relative to the mold. It may be located (position PI) above the mold at a distance of between 1 and 5 cm, and / or between 10% and 100% of the depth of the recess 4 of the mold 2.

[0043] The nozzle 40 may extend substantially perpendicular to the bottom 8, or substantially parallel to the side wall 6. “Substantially” should be understood as a tolerance of + / -10°.

[0044] Alternatively, the nozzle 40 may be movable. For this, an actuator 44 may manipulate the nozzle between an operating position P1 and a rest position P2. The rest position P2 may be further from the mold in a vertical direction and / or in a radial direction. For example, the rest position may be offset, away from the mold so as not to constitute a design constraint for the punch used for thermoforming.

[0045] The installation may also comprise a detector 46. This may be an optical detector, operating in a visible or infrared spectrum. The detector 46 also comprises image processing means in order to determine the position of the spacing E. This position may be expressed in a frame of reference linked to the mold, for example by characterizing the coordinates in a cylindrical frame of reference of the points B and C, or by formalizing the equations defining the curves forming the crescent moon L.

[0046] [Fig.4] illustrates a variation of the use of a nozzle 40 above the mold. In this variant, an orifice 50 or a plurality of orifices 50 is / are arranged on the bottom 8 of the mold. The orifices 50 are supplied with compressed air below the mold. A jet of compressed air can thus be blown from the lower part of the mold.

[0047] The banner 10 may be intentionally positioned such that the spacing E is located above the orifice 50 or orifices 50. Alternatively, the orifices 50 may be arranged on a ring (360°) at the periphery of the bottom 8. The orifices 50 may all be actuated simultaneously. Alternatively, and for example in combination with the detector 42, only the orifices 50 which “see” the spacing E may deliver air pressure. Different air sources or valves may be controlled for this purpose.

[0048] [Fig.4] also shows a variant where a slot 50 is arranged at the bottom of the mold for blowing air. The slot 50 may be rectilinear, or, as drawn, describe an arc of a circle. The slot 50 may be an alternative to the orifices 50, or these may be combined.

[0049] Whether it is the nozzle 40 of [Fig. 3] or the orifices / slot 50 of [Fig. 4], the pressure of the compressed air jet can be between 0.5 and 6 bar. When the section of the nozzle 40 or the slot 50, or when the number of orifices 50 (or their section) are sufficiently large, a low pressure (0.5 to 2 bar) may be sufficient to generate the Venturi effect. The pressure may be constant throughout the operation of placing the banner 10. Alternatively, the pressure may be variable: in this case, it may decrease from an initial pressure to a final pressure which may be less than half the initial pressure. The pressure variations may be controlled as a function of the width e of the crescent moon L, measured in real time by the detector 46.

[0050] Similarly, the blowing duration of the compressed air jet can be predefined. and between 0.3 and 2 seconds, in particular depending on the dimensions of the banner and the mold but also on the speed of the machine. Alternatively, the blowing duration can be regulated according to the data captured by the detector 46, so as to interrupt the jet of compressed air once the banner is pressed against the side wall 6.

[0051] The invention has been described in the context of a pot intended as a food container for liquids or semi-liquids, but other applications are possible, in particular for containing other everyday products (coffee, cereals, detergents, cosmetic or (para)pharmaceutical products, etc.). Also, the invention is not limited to specific shapes or dimensions and may also be applied to containers of all sizes, in particular with a height or width of between 1 cm and several tens of centimeters. List of reference signs

[0052] 1: Sheet before shaping 2: mold 3: support surface 4: recess 6: side wall 8: background 10: paper banner 11: formatted sheet 12: punch 21: pot 22: collar 23: operculum 24: cavity 26: side wall 28: base 30: glue 40: compressed air blowing nozzle 42: compressed air jet 44: nozzle movement actuators 46: E-gap position detector 50: air blowing holes or slots A: radially outer end of the banner B: radially inner end of the banner C: detachment point D: point or middle zone of the crescent moon L e: maximum distance between banner 10 and wall 6 E: spacing zone between banner 10 and side wall 6 L: crescent moon PI: operating position P2: resting position a: angular extent of the spacing zone E.

Claims

Claims

1. A method of manufacturing a food pot (21) comprising the steps of: a. arranging, in a mold (2) having a bottom (8) and a side wall (6), a paper band (10) facing the side wall (6); b. applying a jet of compressed air (42) between the paper band (10) and the side wall (6); then c. thermoforming a sheet of plastic material (1) in the mold (2).

2. Method according to claim 1, in which after the "arrange" step, a crescent moon (L) shaped spacing (E) is formed between the banner (10) and the side wall (6) of the mold (2), the compressed air jet (42) being applied in a middle zone (C) of the crescent moon (L).

3. Method according to one of the preceding claims, in which the compressed air jet (42) is oriented substantially parallel to the side wall (6) of the mold.

4. Method according to one of the preceding claims, comprising, before applying the compressed air jet (42), a step of positioning a removable compressed air blowing nozzle (40) in an operating position (PI).

5. Method according to one of the preceding claims, in which the pressure of the compressed air jet (42) is between 0.5 and 6 bar.

6. Method according to one of the preceding claims, in which the jet of compressed air (42) is applied for a duration of between 0.3 and 2 seconds.

7. Installation (2, 12, 40, 44, 46, 50) for manufacturing food pots configured to implement the method according to one of the preceding claims, the installation comprising: a mold (2) having a bottom (8) and a side wall (6); means (40, 50) for blowing compressed air capable of applying a jet of compressed air (42) between a paper band (10) arranged in the mold (2) and the side wall (6); and thermoforming means (12).

8. Installation according to claim 7, in which the compressed air blowing means (40, 50) comprise a removable nozzle (40). which can be moved by actuators (44) between a rest position (P2) and an operating position (PI).

9. Installation according to claim 8, comprising a detector (46) identifying the position of a spacing (E) between the banner (10) and the side wall (6) of the mold (2) drawing a crescent moon (L), the operating position (PI) being a middle position (D) of the crescent moon (L).

10. Installation according to claim 7, in which the means (40, 50) for blowing compressed air comprise an orifice (50) arranged in the bottom (8) of the mold (2), orifice (50) from which the jet of compressed air (42) is formed.

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