FR2878329A1 - DEVICE AND METHOD FOR REGULAR DYNAMIC PRESSURE - Google Patents

Abstract

The present invention relates to a device and an adjustable dynamic pressurizing method, which find an application in particular to the sealing of sealed packages.The device comprises a means of transport on a plane and in a direction of transport , and a means of holding on this transport plane, a hermetically packaged article. It further comprises a plurality of pressing elements distributed along the transport direction, free of movement along an axis forming with this direction an angle other than 0 ° modulo 180 °. This freedom of movement is between a rest position in which the distance between the pressing elements and the transport plane is minimal, and a maximum position in which the distance between the pressing elements and the transport plane is maximum. Thus, when a transported article is in contact with these pressing elements, the latter pressurize one of the faces of this article by their respective ends. The method of the invention is implemented by the aforementioned device, and preferably comprises a step of classifying the transported article as a function of at least one measurement of the displacement of a first and / or second pressing element.

Description

DEVICE AND METHOD FOR DYNAMIC PRESSURE

ADJUSTABLE

  The present invention relates to a device and an adjustable dynamic pressurizing process, which find an application in particular to the control of the tightness of sealed packages.

  Such sealed packages include vacuum packaging of food products, such as salad sachets for example. These bags can be effectively empty of air or other gases, or filled with a particular gas. In both cases, the packaging must be perfectly hermetic, and it is necessary to check the tightness before leaving the product for marketing. Indeed, a poor seal can cause leakage of the gas contained in the package and / or penetration of outside air inside the package. C) r, this hermetic packaging can for example be intended to promote the conservation of the packaged product, thanks to the presence of gas inside and / or avoiding that the packaged product is in contact with the ambient air which accelerates the degradation of this product, especially if it is a fresh food product.

  There are packaging devices and methods which make it possible to check the tightness or detect leaks in such hermetically sealed packages. These methods consist for example in optically controlling the dimensions of the bag placed in a vacuum chamber, and subjected to a certain pressure, or in detecting leaks of gas escaping from the bag placed in a vacuum chamber, by suction of the gas .

  Such devices and methods are expensive to implement because the technical means for measuring the gas escaping from a bag, or to maintain the vacuum in a chamber in which the bag is placed, are complex.

  Moreover, these devices are not dynamic, insofar as the bag is immobilized during the measurement or detection phase.

  There are of course other devices and methods which make it possible to detect a possible leak during transport of a bag on a conveyor belt, which generally consists in measuring punctually a characteristic value of the package, such as its height or its expansion. (surface contact on the carpet), when it applies a point pressure.

  However, the applied pressure, punctual and momentary, does not allow a possible leak to generate a sufficiently significant variation of the measured characteristic value for it to be detected, especially in case of micro-perforations. Indeed, if such devices can be considered as dynamic insofar as the detection of a possible leakage is carried out during transport of the packaged article, the pressurization, it is not dynamic and n ' is not uniform in time.

  This is why the performances of these systems do not make it possible to detect small and few perforations in a bag. These perforations nevertheless have significant damaging consequences on the packaged article. Conventionally, such devices have detection thresholds of the order of four holes: if the package has only one or two small perforations, the leak is not detected and the packaging is not considered defective , while it should be.

  There is therefore a need for a reliable and more effective solution that overcomes the aforementioned drawbacks. Such a solution must in particular make it possible to detect the perforations in a sealed package with a high detection rate even in the case of a single small perforation in the package.

  Thus, it is the object of the present invention to overcome these disadvantages by providing a device and an adjustable dynamic pressurizing method that allow the detection of leaks in a sealed package from the presence of a single perforation.

  The invention thus relates, according to a first aspect, to an adjustable dynamic pressure device comprising transport means on a plane and in a transport direction, and a means for holding on this transport plane, a article packed tightly.

  The device is characterized in that it comprises a plurality of pressing elements distributed along the transport direction, free of movement along an axis forming with this said direction an angle other than 0 modulo 180. This freedom of movement is between a rest position in which the distance between the pressing elements and the transport plane is minimal, and a maximum position in which the distance between the pressing elements and the transport plane is maximum.

  Thus, when a transported article is in contact with these pressing elements, the latter pressurize one of the faces of this article by their respective ends.

  Preferably, the device comprises means for measuring the displacement, along said axis and relative to its rest position, of at least one first pressing element among all the pressing elements.

  In an alternative embodiment, the device comprises means for measuring the displacement, along the aforementioned axis and with respect to its rest position, of at least one second pressing element among all the pressing elements and situated upstream of the first pressing element.

  Preferably, the device comprises means for classifying the article transported as a function of at least one measurement of the displacement of the first pressing element and / or the displacement of the second pressing element.

  Optionally, the pressing elements are located in the holding means.

  Alternatively, the pressing elements are located in the means of transport.

  Optionally still, the device comprises means for returning the pressing elements in their rest position.

  In an alternative embodiment, the minimum distance between the transport means and the holding means is less than the maximum height of the transported article.

  In another alternative embodiment, which can be combined with the previous one, the minimum distance between the conveying means and the holding means is adjustable.

  Preferably, the transport and / or holding means are provided with several holes.

  Also preferably, the measuring means comprise optical measuring means. These optionally include at least one source and a laser detector.

  The invention also relates, according to a second aspect, to a dynamic pressurizing method implemented by the device according to the invention as described above.

  Preferably, the method comprises a step of classifying the transported article based on at least one measurement of the displacement of a first and / or second pressing member.

  Also preferably, the classification is a function of several measurements of the displacement of the first and / or the second pressing element.

  More preferably, the classification is a function of the average of the measurements of the displacement of the first and / or second pressing element.

  In an alternative embodiment, a transported article is classified in a first category if the measurement or the average of the measurements of the displacement of the first and / or second pressing element is less than a reference value.

  In another variant embodiment, a transported article is classified in a first category if the measurement or the average of the measurements of the displacement of the first pressing element is less than the measurement or the average of the measurements of the displacement of the second pressing element.

  Thus, the device and the method of the invention advantageously make it possible to dynamically put in pressure during transport, an article hermetically closed, in order to detect a possible leak, even in the case of a single small perforation.

  Other features and advantages of the invention will appear more clearly and completely on reading the following description of the preferred embodiments of the device and the implementation of the method, which are given by way of non-standard examples. FIGS. 1a and 1b show diagrammatically the device of the invention in a first variant embodiment, FIG. 2 schematically represents the device of the invention in a second variant embodiment, FIG. 3 schematically represents the device of the invention in a third variant embodiment, FIG. 4 schematically represents an embodiment of the pressing elements, with means for measuring the displacement of a pressing element, of the device of FIG. invention.

  Figures 1a and 1b show schematically the device of the invention in a first embodiment.

  The device comprises a means 1 for transporting an article 3 on a transport plane P, and in a transport direction D. This transport means 1 may conventionally be a modular chain, a conveyor belt, or a set of rollers . The article 3 transported may be for example a sealed salad bag.

  The device further comprises a means 2 for maintaining the article 3 transported on the means 1 of transport. As for the means 1 of transport, this means 2 of maintenance can be classically a modular chain, a conveyor belt, or a set of rollers.

  In this embodiment variant, pressing elements 4,4 ', 4 "are arranged in the holding means 2. These elements are of the lamella type, preferably, but not necessarily, of plastic material and are free of movement according to the invention. A vertical axis, therefore perpendicular to the direction of transport D which is horizontal.This freedom of movement is between a rest position, in which the distance between these slats and the transport plane is minimal, and a maximum position in which this same distance is maximum, it can be seen, for example in FIGURE 1a, that the lamella 4 "is in the rest position, and that the minimum distance between the lamellae in the rest position and the transport plane corresponds to the distance between the band of the means 1 of transport and that of the means 2 of maintenance.

  The bag 3 thus undergoes firstly a progressive introduction at the input of the device (FIG. 1a), that is to say, upstream of the direction D of transport, then evolves between the two bands, or between the two means 1 and 2 respectively of transport and maintenance, towards the output of the device (Figure 1b), that is to say downstream of the direction D of transport.

  In FIG. 1a, the lamella 4 'is no longer in the rest position and undergoes a displacement of (materialized through the fictitious dotted line 11), as a result of the passage of the bag 3 which raises it and which, in return, is urged in pressure, at its surface 3a, by the end 4a 'of the lamella 4'. The lamella 4 'can not be raised beyond a limit represented by the fictitious dotted line 10. The same applies to the lamella 4 of FIG. 1b, which is in the rest position in FIG. . In this figure 1b, we see also that the plate 4 ', which was raised in Figure la, is in the rest position. Thus, as the sachet 3 passes, the lamellae 4, 4 ', 4 "rise and, in return, apply pressure at their respective ends 4a, 4a', 4a" to the surface 3a of the bag 3.

  Preferably, the distance between the means of transport 1 and the holding means 2 is less than the maximum height of the bag 3 transported, in order to ensure that the pressurization is sufficient.

  Optionally, this distance can be adjustable, to make the device adaptable to any type of article 3 transported regardless of its dimensions, thus ensuring that the distance between the means 1 of transport and the means 2 of maintenance is less than the maximum height of this item 3 transported regardless of its dimensions.

  In Figures la and 1b, there are also means 5, 6 measuring whose role is to measure the respective displacements of the lamellae 4 and 4 '.

  The details of the position of rest, the maximum position, and the displacement d, of lamellae, and as to the means 5,6 of measurement, and measuring principle, of the displacement d, of. lamellae 4,4 ', are presented in more detail below, with reference to FIG.

  The bag 3 is thus maintained under uniform pressure between the means 1 of transport and the means 2 of maintenance.

  As it passes under the lamella 4 '(FIG. 1a), the sachet 3 lifts the latter from a displacement of which varies chronologically from 0 to a maximum value for a given sachet, then from this maximum value to O. The measuring means 6 determine the value of d. These measuring means may be optical measuring means, such as a laser source with laser detector. They can make a single measurement, or preferably, several successive measurements.

  The same remarks apply to slat 4 (in FIG. 1 b) and to measurement means 5.

  Thus, if the bag 3 is perforated, the uniform pressurization, carried out throughout the transport of the inlet to the outlet of the device, accelerates the leakage and therefore the flattening of the bag 3. Preferably the strip or belt constituting the transport plane P in the means 1 of transport, said lower band, is perforated, so as to facilitate the escape of the gas in case of leakage in the bag 3, as it is transported and put in pressure. The band constituting the holding plane in the holding means 2, said upper band, can also be perforated for the same purpose. We can choose to perforate the lower band and / or the upper band, or neither.

  The method therefore consists in measuring preferably several values of the displacement of the lamella 4 ', and preferably several values of the displacement d of the lamella 4. These values of the displacement d are then compared with the values of the displacement of, for example through the respective averages. If the average of the values of d is less than the average of the values of d, a leak is characterized and thus detected. The bag 3 is thus classified as defective.

  The ranking is achieved through the means 7,8,9 ranking, which perform for example the calculation and comparison of averages. These means may for example return the information to make it available to an operator, for example by a display.

  The display is then for example followed by manual sorting by the operator who decides the classification of the article based on the information displayed.

  Preferably, the grading means are connected to a device for ejecting the defective pouches at the outlet of the device according to the invention, or to guide them out on a different conveying path.

  It is understood that the method and the device operate with a single measurement of the displacement of the lamella 4 and the lamella 4 '. However, for effective detection of leaks, it is obviously preferable to carry out several measurements for each of the lamellae 4 and 4 '.

  Furthermore, the method and the device also operate with a single measuring point, materialized by the strip 4, which is then located sufficiently downstream of the transport to allow sufficient pressurization upstream through all the 4 "upstream of the lamella 4. A measurement of the displacement d at this single measurement point of the lamella 4, or a series of measurements of this displacement d, is then compared with a reference value, or a profile of values. If the value or the profile of measured values is lower than the value or profile of reference values, the bag is classified as defective, but it will be understood that the method of the invention with a single downstream measuring point n is effective only if a reliable value or a profile of reference values can be available.

  FIG. 2 diagrammatically represents the device of the invention in a second variant embodiment.

  In this variant embodiment, the device is identical to that of FIGS. 1a and 1b, with the exception of the transport plane P and the transport direction D which are not horizontal. They are indeed inclined at an angle to the horizontal, to meet a need for transport on an inclined plane to bring the products transported to a given height. In this example, the transport direction D is rising, but it can also be descending without departing from the scope of the invention.

  It can be seen in this FIG. 2 that the lamellae 4,4 ', 4 "are free of movement along the axis A, which is always perpendicular to the transport direction D or to the transport plane P. To ensure a return to position of the slats, after the passage of the article 3 transported, it is preferable to add to these slats 4,4 ', 4 "means 41,41', 41" restoring position in the rest position. for example, it may be simple springs which are in the rest position when the slats are in the rest position, and compressed when these slats are raised.

  However, it can also be envisaged that the axis A remains vertical, to ensure a good pressure on the surface 3a of the article 3 transported. This then requires taking into account, when measuring the displacement d, 4,4 'lamellae, the inclination of the transport, for example by correctly orienting the measuring means 5, 6.

  For the device and the method to function correctly, it must however be ensured that the axis A does not make an angle of 0 modulo 180 with the direction D of transport, in which case the pressure loading of the surface 3a of the article 3 carried by the ends 4a, 4a ', 4a "of the lamellae 4,4', 4" would become impossible.

  Figure 3 schematically shows a third alternative embodiment of the device of the invention.

  In this variant embodiment, the lamellae 4,4 ', 4 "are located in the means 1 of transport.

  In this case, regardless of the angle that the axis A with the direction D of transport, the presence of the means 41,41 ', 41 "of return of the slats 4,4', 4" in the rest position is indispensable.

  FIG. 4 diagrammatically represents an exemplary embodiment of the pressing elements, or lamellae, with means for measuring the displacement of one of these lamellae, of the device of the invention.

  It can be seen in this FIG. 4 that each lamella 4,4 "can slide in a housing delimited by the walls 11 and 12 in the case of the lamella 4. The displacement of the lamella 4 is limited downwards by the element 13, and upwards by the element 14. The elements 14 respectively associated with each of the lamellae 4,4 "(and 4 'with reference to the preceding figures) are aligned and form the fictitious dotted line 10 of the preceding figures.

  An element 15, angle type, is attached to the blade 4, and follows it in its movements.

  The measuring means comprises a laser source and a laser detector. The laser source emits a light beam which bounces on the angle 15 and the beam thus reflected is detected back by the detector. The conventional calculations of the state of the art make it possible to determine the distance between the angle and the laser detector 5, and therefore, consequently, the displacement of the lamella 4.

  The angle is of material having sufficient reflective power. It may be for example a metallic material.

  The whole of the description above is given by way of example, and is not limiting of the invention. In particular, it will be recalled that the presence of two measurement points, at the level of the lamellae 4 and 4 ', is not limiting of the invention. A single measuring point, at the level of the lamella 4, located sufficiently downstream of the transport direction D, and preceded, upstream, by a sufficient number of lamellae 4 "to ensure the pressurization, allows the device and the method of the invention to fulfill its role.

  Moreover, it will also be recalled that the choice of the average as a mathematical function representative of the set of displacement values measured for a given plate, is also not limiting of the invention. As previously explained, a single value may suffice. And in the case of a plurality of measurements, it is possible to envisage other mathematical functions representative of the profile of measured values.

  Finally, it will be recalled again that the axis A according to which a sliding strip does not necessarily make a right angle with the transport direction D. Depending on the circumstances and the variant embodiments, the angle may be greater or smaller than a right angle , provided that the pressing elements can exert sufficient pressure on the transported article. This angle must not be a flat angle, that is to say, it must not be equal to 0 modulo 180.

Claims (1)

12 CLAIMS   An adjustable dynamic pressure device comprising means (1) for transporting on a plane (P) and in a direction (D) of transport, and means (2) for holding on said transport plane (P), of an article (3) hermetically packaged, characterized in that it comprises a plurality of pressing elements (4,4 ', 4 ") distributed along said direction (D), free of movement along an axis (A ) forming with said said direction (D) an angle different from 0 modulo 180, between a rest position in which the distance between said pressing elements (4,4 ', 4 ") and said transport plane (P) is minimal, and a maximum position in which the distance between said pressing elements (4,4 ', 4 ") and said transport plane (P) is maximum, so that the respective ends (4,4a', 4a") of said pressing elements (4 ") pressurize one (3a) of the faces of said article (3) when the latter is in contact with said so-called pressing elements s (4,4 ', 4 ").   2. Device according to claim 1, characterized in that it comprises means (5,6) for measuring the displacement (d), along said axis (A) and with respect to said rest position, of at least one first pressing element (4) among said pressing elements (4,4 ', 4 ").   3. Device according to claim 2, characterized in that it comprises means (5,6) for measuring the displacement (d "), along said axis (A) and with respect to said rest position, of at least a second pressing element (4 ') of said pressing elements (4', 4 ") and located upstream of said first pressing element (4).   4. Device according to any one of claims 2 and 3, characterized in that it comprises means (7,8,9) for classifying said article (3) according to at least one measure of said request n O42 $ 7 b329 moving (d) said first pressing member (4) and / or said displacement (d ') of said second pressing member (4').   5. Device according to any one of claims 1 to 4, characterized in that at least one of said pressing elements (4,4 ', 4 ") is located in said means (2) for holding.   6. Device according to any one of claims 1 to 5, characterized in that at least one of said pressing elements (4,4 ', 4 ") is located in said means (1) of transport.   7. Device according to any one of claims 1 to 6, 1 o characterized in that it comprises means (41,41% 41 ") for biasing said pressing elements (4,4 ', 4") in their position rest.   8. Device according to any one of claims 1 to 7, characterized in that the minimum distance between said means (1) for transport and said means (2) for holding is less than the maximum height of said article (3) transported 9 Device according to any one of claims 1 to 8, characterized in that the minimum distance between said transport means (1) and said holding means (2) is adjustable.   10. Device according to any one of claims 1 to 9, characterized in that said means (1) for transport and / or means (2) for holding are provided with several holes.   11. Device according to any one of claims 2 to 10, characterized in that said measuring means (5,6) comprise optical measuring means.   12.Dispositif according to any one of claims 2 to 11, characterized in that said measuring means (5,6) comprise at least one source and a laser detector.   13. A method of dynamically pressurizing an article (3) hermetically packaged, on a plane (P) and in a direction (D) of transport, characterized in that it comprises at least one pressure step of said pressure article (3) by one or more request n2878329 pressure elements (4.4 ") free movement along an axis (A) forming with said direction (D) an angle other than 0 modulo 180.   14. The method as claimed in claim 13, characterized in that it comprises a step of classifying said article (3) transported as a function of at least one measurement of the displacement (d, d ') of a first and / or second pressing element (4,4 ') along said axis (A).   15. The method of claim 14, characterized in that the classification carried out in said classification step is a function of several measurements of said displacement (d, d ') of said first and / or second pressing element (4,4').   16. The method of claim 15, characterized in that the classification carried out in said classification step is a function of the average of said several measurements of said displacement (d, d ') of said first and / or second pressing element (4,4'). .   17. Method according to any one of claims 13 to 16, characterized in that a item (3) transported is classified in a first category if said measure or said average of said several measures of said displacement (d, d ') of said first and / or second pressing element (4,4 ') is less than a reference value.   18. Method according to any one of claims 13 to 16, characterized in that a transported article (3) is classified in a first category if said measure or said average of said plurality of measurements of said displacement (d) of said first pressing element ( 4) is less than said measurement or said average of said plurality of measurements of said displacement (d ') of said second pressing member (4).