Packaging line with means for marking molluscs and corresponding method
The present invention relates to the marking of molluscs with an external shell, and more particularly to the engraving of live oysters on a packaging line.
In general, the only indications for telling a customer about the origin of an oyster or any other mollusc are those present on the hygiene label and also those on the packaging.
However, there is no information on the product as such, that is to say on the mollusc.
Documents EP 1 994 830 A1 and WO 2009/141002 A1 disclose a method and a system for identifying a crustacean comprising engraving means able to engrave an imprint on a shell and control means able to control the engraving of the imprint on the shells of the molluscs placed in the housings of a loading tray.
Document WO 98/42197 Al discloses a method and a station for orientation of molluscs with an external shell comprising trays for loading molluscs with an external shell provided with housings for receiving a mollusc and carried by a transfer conveyor.
The invention proposes solving this problem with the aid of a marking device for realizing systematic identification of each oyster, or of each mollusc, in order to reliably guarantee the origin of the products to the end consumer, but also to protect the producer from any imitations.
According to one aspect of the invention, there is proposed a packaging line for molluscs with an external shell according to claim 1 with a device for marking molluscs with an external shell comprising laser engraving means that are able to engrave an impression onto a shell, and control means that are able to control the engraving of the impression onto the shells of the molluscs located in compartments in a loading tray.
The shell of an oyster is formed from layers of mineral and organic materials.
It has very variable colorations, thicknesses and hardnesses, depending on the origin of the oysters.
The multicoloured nature of the oyster shell does not make it possible to systematically obtain optimal legibility with common marking methods such as inkjet printing, no matter which ink is used.
This problem is also encountered in the marking of other molluscs.
Laser engraving makes it possible to produce a marking by taking away material.
The removal of material from the surface of the shell of an oyster or of another mollusc makes it possible to obtain a colour contrast that renders the marking visible by clear differentiation and makes it easier to read, regardless of the colour of the shell.
The impression engraved on the shell may be for example a brand or a logo, a date, or a unique identification code for each oyster, such as an identification number, a barcode, or any other identification code.
Preferably, the laser engraving means comprise at least one carbon dioxide laser with a power of between 50 W and 70 W, more particularly 60 W.
The use of a carbon dioxide laser with a power of 60 W makes it possible to avoid any risk of piercing the shell of an oyster during engraving, and to protect the live oyster by also avoiding prolonged exposure to the heat source.
For other molluscs, the power can be adapted depending on the type and thickness of the shell of the mollusc.
In one embodiment, the laser engraving means comprise a number of lasers eguivalent to the number of compartments in a loading tray of a transfer conveyor, the lasers being disposed so as to be located respectively opposite a compartment when a loading tray is positioned opposite the marking device.
The plurality of lasers used makes it possible to reduce the engraving time and to increase the rate on a marking line of a packaging line.
In one variant, the laser engraving means comprise a single laser and means for moving in translation that are able to move the laser opposite each compartment in a loading tray of a transfer conveyor in order to engrave each mollusc on the tray.
In another variant, the laser engraving means comprise a single laser associated with optical elements that are orientable and movable so as to allow the six molluscs on a single tray to be engraved in succession without the laser being moved.
The use of a single laser makes it possible to reduce the production costs of the marking device.
According to a general feature, the packaging line comprises loading trays for molluscs with an external shell, said loading trays being provided with compartments for receiving a mollusc and being carried by a transfer conveyor, and a marking device as defined above that is able to engrave an impression onto the shell of each mollusc located on a loading tray.
In order to ensure that the products are transferred to the marking station, the conveyor may be a conveyor of the racetrack type.
Preferably, the loading trays comprise nonslip surfaces in the bottom of each compartment.
The size and shape vary greatly from one oyster to another.
The size varies in three dimensions: length, width and thickness.
This parameter creates problems with stability and the positioning of the oyster before and during the marking phase, causing rejects.
By using trays having individual compartments on the conveyor, it is possible to limit these phenomena.
The individual compartments are designed to receive molluscs of different sizes, and in particular oysters of any grade.
For this purpose, the individual compartments each have for example a size that makes it possible to receive an oyster of the largest grade.
The mollusc is disposed so as to have its flattest side in contact with the nonslip surface.
The oyster, for example, is disposed in the compartment such that the side of its shell having a flat surface is in contact with the nonslip surface of the compartment.
Advantageously, each compartment of a loading tray may comprise at least two positioning cleats that define at least one corner of the compartment and are able to retain a mollusc in the compartment.
The disposition of the mollusc in abutment against the two cleats that form a corner of the compartment ensures that the mollusc is aligned and centred with respect to the three axes, while limiting the phenomenon of sliding.
The packaging line may also comprise line timing means that are able to advance the trays sequentially such that one tray is at a standstill when the marking device is acting on the oysters on the tray.
The timing means can control the transfer conveyor such that the latter advances the loading trays in a sequential manner.
The timing means can also be coupled to the marking device so as to synchronize the movement of the trays and the engraving of the molluscs on the trays.
According to yet another aspect of the invention, there is proposed a method of packaging molluscs with an external shell according to claim 10 comprising loading of molluscs onto a loading tray, moving of the tray by way of a transfer conveyor and marking of the shell of the molluscs.
The marking may be carried out by laser.
Advantageously, the movement may be timed sequentially such that a pause is made after each movement of the tray by the transfer conveyor.
Further advantages and features of the invention will become more apparent from examining the detailed description of an embodiment and an implementation mode, which are entirely nonlimiting, and the appended drawings, in which:
- Figure 1 schematically illustrates a perspective view of a transfer conveyor provided with loading trays for molluscs according to one embodiment of the invention;
- Figure 2 schematically illustrates a top view of a loading tray for molluscs of the conveyor from Figure 1; - Figure 3 schematically shows a marking line of a packaging line comprising the transfer conveyor from Figure 1;
- Figure 4 shows a flow chart of a method for packaging molluscs according to one implementation mode of the invention.
Figure 1 schematically shows a perspective view of a transfer 5 conveyor 1 provided with loading trays 2 for molluscs, in particular oysters, according to one embodiment of the invention.
The transfer conveyor 1 is a chain conveyor comprising a frame (not shown) formed by guides 20 that support two transfer chains 3. The chains 3 are provided with projections 4 to which the loading trays 2 are fixed.
The chains 3 are mounted on two toothed pinions 21 and 22 that are each disposed at one end of the conveyor 1, one of the pinions 21 being motor-driven so as to generate the driving movement of the conveyor 1.
In the embodiment illustrated in Figure 1, each loading tray 2 comprises six individual compartments 5. As is illustrated in Figure 2, which shows a top view of a loading tray 2 for oysters H, each compartment 5 of the loading tray 2 comprises a nonslip surface 6 and two cleats 7 that define a corner of the compartment 5.
The nonslip surface 6 is disposed on the entire surface of the compartment 5 so as to keep the oyster H in position and avoid any sliding of the oyster H during the movement of the tray 2. In order to maximize the adhesion of the oyster H to the nonslip surface 6 of the compartment 5, the side of the oyster H shell that has the flattest surface is placed in contact with the nonslip surface 6.
In addition, by covering the entire surface of the compartment 5 with such a nonslip surface 6, an oyster H of any grade can be placed in the compartment 5 and be kept correctly in position.
In order to enhance the keeping in position of the oyster H and also to centre the oyster H in the compartment 5, the cleats 7 are disposed on two edges that form a single corner of the compartment 5 so as to define a rim of the corner.
Each oyster H is thus placed in a compartment 5 with the flat side in contact with the nonslip surface 6 and so as to be in contact with the two cleats 7.
The oysters H are sorted by grade before being supplied to and disposed on the trays 2 of the transfer conveyor 1, such that the oysters H of a single grade arc engraved during a marking session. Thus, positioning the oysters H against the two cleats 7 ensures that the engraving is carried out systematically on the same region of the shell. Figure 3 illustrates a marking line 8 of a packaging line comprising the transfer conveyor 1 from Figure 1. The marking line 8 comprises the transfer conveyor 1, a feed conveyor 9 that delivers oysters of a single grade, a marking device 10 and a vessel 11 for collecting the marked oysters. The feed conveyor 9 is juxtaposed in a parallel manner with the transfer conveyor 1. In this way, one or more users can distribute the oysters conveyed by the feed conveyor 9 into the compartments 5 of the loading trays 2 of the transfer conveyor 1. The oysters thus disposed and centred in the compartments 5 of the loading trays 2 by virtue of the cleats 7 are conveyed to the marking device 10 by the transfer conveyor 1. The marking device 10 is disposed above the transfer conveyor 1 in a region close to the outlet end 12 of the transfer conveyor 1. In this embodiment, the marking device 10 comprises six carbon dioxide lasers that are mounted so as to each be opposite a compartment 5 of a tray 2 when a loading tray 2 is positioned under the marking device
10. Of course, the number of lasers corresponds to that of the compartments 5 in the loading trays 2. The lasers have a power of between 50 W and 70 W, and preferably around 60 W so as to allow visible engraving of the shell without there being a risk of piercing the shell of the oyster. The marking device 10 comprises means for positioning the lasers that make it possible to move all of the lasers together such that they are each opposite a single area of the compartment 5. The marking device 10 also comprises control means for controlling the engraving of an impression on the shells of the oysters disposed in the compartments 5 of a loading tray 2. The control means have a parameterizable module that makes it possible to define the impression to be engraved and a synchronization module that makes it possible to synchronize the movement of the transfer conveyor 1 with the lasers of the marking device 10. In this embodiment, the transfer conveyor 1 is timed so as to make a pause between each movement of the chains 3 carrying the loading trays 2. Such timing of the transfer conveyor 1 makes it possible to keep each loading tray 2 stationary under the marking device 10 for a period of time necessary for engraving the impression on the shell of the oysters. Once the impression has been engraved on the oysters on a loading tray 2, the transfer conveyor 1 is actuated so as to convey another loading tray 2 under the marking device 10. The loading tray 2 on which the oysters have been engraved is simultaneously conveyed to the outlet end 12 of the transfer conveyor 1, such that the oysters are discharged into the collecting vessel 11. When the loading tray 2 is conveyed to the outlet end 12 of the transfer conveyor 1, the tray 2 tips so as to discharge the oysters into the vessel 11. The vessel 11 may comprise a hamper disposed so as to receive the six marked oysters. The hamper is then closed after having received a multiple of six oysters and replaced with another hamper ready to receive the next marked oysters. Figure 4 shows a flowchart of a method for packaging molluscs according to one implementation mode of the invention. In a first step 100, a mollusc is disposed in a centred manner in each of the compartments 5 of a loading tray 2 of a transfer conveyor
1. In a following step 200, the transfer conveyor 1 conveys the tray 2 thus loaded into a position in which the molluscs disposed in the compartments 5 in the tray 2 are each opposite a carbon dioxide laser of a marking device 10. The tray 2 is moved in a timed manner by the transfer conveyor 1, that is to say in a sequential manner, such that the tray 2 pauses prior to movement again.
In a step 300, the oysters in the tray disposed under the marking device 10 are engraved.
The engraving is carried out by regulating the lasers to a power of 60 W and by respecting an exposure time that is sufficient to engrave the impression without piercing the shell or exposing the oyster to an excessive overall quantity of heat.
In a final step 400, the marked oysters are discharged into a collecting vessel 11 in order to pack the oysters and finalize the packaging of an oyster hamper.
The invention thus makes it possible to realize systematic identification of molluscs directly on their shell with the aid of a packaging line having a marking device, thus making it possible to reliably guarantee the origin of the products to the end consumer, but also to protect the producer from any imitations.
Finally, it should be noted that the invention is not limited to the above embodiment, but to the subject matter of the appended claims.
Specifically, in the marking device described, the engraving means have a set of lasers, the number of which corresponds to the number of compartments in the loading tray.
Of course, if the engraving means of the marking device comprise a single laser and the means for moving in translation that are able to move the laser opposite each compartment in a loading tray of a transfer conveyor in order to engrave each mollusc on the loading tray, this does not constitute a departure from the scope of the invention.