HK1215425B - Package, method for manufacturing a package, and mold for application for the purpose of such method - Google Patents

Description

Package, method for manufacturing a package and mould for applying such a method

Technical Field

The present invention relates to a package comprising: a unitary tray having an open side and an annular cover rim at the open side of the tray and at an outer peripheral edge of the tray, and connected to the tray by a relatively weak breaking portion. The invention also relates to a method of manufacturing such a package and to a mould for applying such a method.

The packages described in the foregoing are generally made of plastic and may be used for the purpose of packaging food products, for example.

Background

One example of a method for manufacturing a package with an integrated tray, a rupture portion and a lid edge is shown in FR 2618411. According to a known method, in order to seal the tray of the package, a piece of cover foil is provided, which is connected at least to the cover rim of the package and possibly also to the tray. In the first use of the package, the user breaks the rupture portion between the lid edge and the tray, and then pulls the entirety of the lid edge and the lid foil away from the tray, wherein a possible connection between the lid foil and the tray is interrupted. From the first use, the whole of the cover rim and the cover foil (hereinafter referred to as cover) can be put back on the tray or removed from the tray again, depending on preference. Near the open side, the tray has a recess into which a portion of the cover rim can be inserted in order to be able to establish a temporary connection between the cover and the tray repeatedly in accordance with this. The tray and the cover rim are manufactured as one piece by injection moulding, wherein on the one hand the rupture portion is thick enough to allow the plastic to flow through this portion in the injection moulding process and on the other hand the rupture portion is thin enough to allow the user of the package to detach the cover rim from the tray at the first use.

An important advantage of the known method is that the inner space of the tray can be completely sealed from the environment before the first use. The connection between the cover foil and at least the cover rim can be realized along the entire circumference of the cover rim so that the connection is free of any interruption, which could be a leakage between the inner space of the tray and the outside. Another important advantage is that material is saved by allowing the cover foil, which in the first example is used to completely seal the inner space of the tray, to be an integral part of the cover. This is in contrast to many common cases where a piece of cover foil is first attached to a tray and then the entire cover is placed on the sealed tray, usually covering the cover foil by a snap-fit connection. In this case, at first use, the user removes the cover from the tray and then pulls the cover foil away from the tray and discards the cover foil, or possibly leaves the cover foil at the tray, which is in an only partially detached state. In any case, the cover foil then no longer has a sealing function. After the first use, only the cover is actually used and no longer has a sealing function.

Especially when packaging food products, it is important to seal the tray in a reliable manner before the first use. In this case, there is virtually no risk that the tray may be opened inadvertently, and that the contents of the tray are wasted. For certain types of food products it is important to have a hermetic seal, since in this case a certain shelf life of the packaged food product can be guaranteed.

WO 2005/039997 relates to a method for manufacturing a package with a tray and a lid comprising a lid rim and a piece of lid foil, wherein the tray and the lid rim are formed separately from each other and then put together, or wherein the tray and the lid rim are connected to each other by one or more small pieces of material, which in this case acts as a hinge. In both cases, the cover rim needs to be first placed on the tray in the correct way before the cover foil is applied.

DE 9311330 shows a package with an integrated tray, a breaking portion and a cover rim, wherein the open side of the tray is sealed by a piece of cover foil connected to the cover rim, and wherein the breaking portion and the cover rim enclose an outer circumferential rim of the tray. Before the first use, the surface of the cover rim to which the cover foil is connected is at a higher level than the outer circumferential rim of the tray. Once the rupture portion is ruptured, the entirety of the lid rim and the lid foil can be placed back onto the tray as a lid, wherein the inwardly projecting portion of the lid rim engages under the outer peripheral rim of the tray.

A disadvantage of the method known from FR 2618411 is that the design of the package is in fact only capable of producing the integrated tray, rupture portion and lid edge by injection moulding. Reference is made to the method of manufacturing the package known from DE 9311330, as such. A disadvantage of the method known from WO 2005/039997 is that an additional step of placing the cover rim on the tray needs to be performed before the cover foil can be applied to the assembly of tray and cover rim.

Disclosure of Invention

It is an object of the present invention to provide a method of manufacturing a package having a tray, a rupture portion and a lid edge, wherein the manufacturing process may be efficient and relatively low cost, as the package is typically a product suitable for mass production, which is desirable, and wherein also a reliable sealing of the tray before first use, in particular by a piece of lid foil, can be provided to obtain the advantage of saving material and to avoid that the lid foil no longer has a function after first use, as described above.

The set aims are achieved by a method of manufacturing a package comprising: -a unitary tray having an open side and an annular cover rim at the open side of the tray and at an outer circumferential edge of the tray, and which is connected to the tray by a relatively weak breaking portion, wherein a mould is provided, wherein a sheet is provided and placed in the mould, and wherein the sheet is forced to move in two different directions in order to form the sheet into a package with the tray and the cover rim.

According to the invention, the integrated tray, the breaking portion and the lid rim are manufactured on the basis of a sheet forming the desired shape in a mould, wherein the sheet is forced to move in two different directions. In a practical way of carrying out the invention, the lamellae are planar in a first example. In this case, the sheet is forced within the mold to form the sheet into the desired shape defined by the mold. This can be achieved, for example, by employing a technique known as vacuum forming or thermoforming. Generally, by means of such techniques known per se, the material is first heated and then plastically deformed. These techniques are in fact suitable for the mass production of the formed products in planar sheets, which are also denoted as foils or plates, for example.

If vacuum forming or thermoforming is applied to mass production, the method is a relatively inexpensive manufacturing method. Furthermore, vacuum forming or thermoforming offers the possibility of using various types of plastic, including PVC (polyvinyl chloride), PET (polyethylene terephthalate) and APET (amorphous polyethylene terephthalate) or multilayer foils with suitable composition, e.g. PP EHOV PP (polypropylene ethylene vinyl alcohol polypropylene). In particular, multilayer foils are very suitable for use in packaging food products due to their good barrier properties, i.e. they are very well able to prevent gas exchange between the sealed interior of the package and the environment of the package. This is advantageous for the shelf life of food products packaged in a protected environment, as it prevents oxygen in the air from entering the package interior too quickly.

In vacuum forming or thermoforming, it is common practice to subject the sheet to force in only one direction. In contrast, the present invention provides for forcing the sheet to move in two different directions. Preferably, the area of the lamella designated for constituting the breaking portion constitutes a separation between two differently directed forming movements, so that the lamella is fixed in position at the portion and can be weakened in the desired manner by applying a suitable tool. In a practical sense, the portion of the sheet may be an annular portion which is clamped for the purpose of the forming process, wherein a portion of the sheet towards the inside of the annular portion and a portion of the sheet towards the outside of the annular portion are moved in two different directions.

Preferably, the sheet is forced to move in the two different directions simultaneously. As a result, the forming process can take place in as short a period of time as possible. In any case, according to the present invention, it is possible to have a degree of freedom in designing the tray and the cover rim that is higher than when the sheet is forced in a single direction to form the tray and the cover rim. Furthermore, the design of the mould has a greater freedom, without causing difficulties in terms of releasing the integrated tray, rupture portion and lid rim from the mould.

EP 1930253 discloses a package having an integrated tray, a breaking portion and a cover rim, wherein the open side of the tray is sealed by a piece of cover foil connected to the cover rim, and wherein the breaking portion and the cover rim enclose an outer circumferential rim of the tray. In a first example, the integrated tray and cover rim are manufactured by vacuum forming or thermoforming, and then the rupture portion is realized by perforating between the tray and cover rim. Unlike in the case of the present invention, different portions of the sheet do not move in different directions when forming the integrated tray and cover rim. The design of the package is thus suitable for being realized in a conventional manner by vacuum forming or thermoforming, wherein a single direction of force of the sheet is used.

Once the rupture portion of the package known from EP 1930253 is ruptured, the integral lid rim and lid foil can be replaced as a lid onto the tray and connected to the tray. To this end, the lid rim has a plurality of projections and the tray has a plurality of recesses in the outer peripheral rim. By positioning the cover rim relative to the tray in such a way that the protruding portion of the cover rim is aligned with the recess in the outer peripheral rim of the tray, and then rotating the cover rim relative to the tray along an angle of about 45 °, the user of the package can establish a detachable connection between the integrated cover rim and cover foil on one hand and the tray on the other hand, as desired. This requires precise activity by the user, which is undesirable in the context of simple items (e.g., packaging) that are used on a daily basis. Within the framework of the invention, the package can have a design in which the lid edge has an inner ring in which there is an inward bulge (bulge) along at least a part of its circumference. The projection has the function of establishing a clamping connection between the cover rim and the tray, achieving a correct, centred position of the cover rim relative to the tray. When pressed on the cover rim on the tray, the inner ring of the cover rim and the tray at the position of the outer peripheral rim are pressed inwards in a resilient manner until the protrusion reaches a position beyond the peripheral rim of the tray. At this point, the inner ring of the cover rim and the tray at the location of the outer peripheral rim can again be moved outwards in an elastic manner, wherein a clamping connection is obtained between the cover rim and the tray. Unlike in the state of the art, the user of the package according to the invention does not need to make any effort to place the tab in the recess to secure the lid edge on the tray. Instead, the described projections are provided as an aid, wherein the cover rim can be placed on the tray in any rotational position, and wherein a connection between the cover rim and the tray is sufficient only by a downwardly directed linear movement of the cover rim relative to the tray.

This is useful when the mould comprises a plurality of individual elements including: a first forming element having a forming surface shaped according to a bottom surface of the tray; and a second profiled element having a profiled surface profiled in accordance with the upper surface of the lid rim. In this case, the foil is placed in a mould, wherein the first forming element is located on one side of the foil and the second forming element is located on the other side of the foil, wherein the foil is clamped between the parts of the first and second forming elements facing each other. Furthermore, the first forming element is surrounded by a movably arranged tubular punching knife. According to the invention, the sheet is forced in two opposite directions with respect to the portions of the first and second forming elements facing each other, between which it is gripped, so as to place the first portion of the sheet in contact with the forming surface of the first forming element and thus constitute the tray, and the second portion of the sheet in contact with the forming surface of the second forming element and thus constitute the cover edge. The punching blade is moved in the direction of the sheet and is partly pressed in the sheet in order to obtain a rupture portion between the tray and the edge of the cover.

By applying a serrated punching blade, areas of weaker and less weak fracture parts can be obtained as desired. As a result, the punching blade can perform a single, relatively simple movement. For example, by applying a punching knife, an opening can be obtained between the tray and the edge of the cover at a defined location. In this case, the breaking portion is perforated, with the result that the breaking portion can be broken even by hand.

Within the framework of the invention, the package can be separated from the surrounding sheet material while the punching blade is moving within the sheet. In this case, after the forming process, the package is completed in a single punching movement, as before. This is advantageous when seeking to spend as little time as possible in manufacturing the package. At the same time, it may be helpful to spend less time performing the activity. This does not alter the fact that: within the framework of the invention, these activities can also be carried out in a continuous manner.

In a practical application of the method according to the invention, the foil is heated before it is formed. In general, it can be assumed that the material of the sheet is more easily deformed under heated conditions than under unheated conditions. In any event, this is the case with many common types of plastics.

By applying a pressure differential over the sheet, the forming movement of the sheet within the mold can be achieved as desired. For example, a low pressure may be generated in the areas where the lamellae need to be moved in the direction of the surface of the mould, and/or an overpressure may be generated on the other side of which areas of the lamellae, wherein in this case compressed air may be used. For the sake of completeness, it is to be noted that it is advantageous in this case when the lamellae are clamped in an airtight manner during the manufacture of the package, so that virtually no leakage of compressed air between the regions of the lamellae formed in different directions occurs.

The package obtained by applying the method according to the invention can be provided in a simple manner with a piece of cover foil for sealing the package. In this case, the piece of cover foil is connected to at least the cover rim. This can be done with the lid edge and the tray connected to each other by the rupturing portion, and also after the first rupture of the rupturing portion. In this case, the cover rim and the tray are separated from each other by forcing them into a limited relative movement in which the rupture portion ruptures. In this case, the rupturing may be carried out mechanically, while in the first case the user of the package typically ruptures the rupturing portion by hand. With reference to the first case, it is furthermore noted that a package is obtained in which the cover foil is located at a higher level with respect to the bottom of the tray before the first use than when the rupture portion is ruptured. Specifically, in the normal direction of the package (the opening side of the tray is located on the upper side, and the bottom of the tray is located on the lower side), at least a part of the lid body edge can protrude upward from the breaking portion with respect to the tray when the breaking portion has not been broken. The cover foil is then folded back onto the tray, wherein the cover foil is folded back onto the tray, and the cover edge is folded back onto the tray, wherein the cover foil is folded back onto the tray. Since a portion of the contents is removed for consumption, the lower level of the lid after the first use does not constitute a problem, assuming that the contents of the package decrease with the first use. Particularly when the package is used for packaging food products, for example, for packaging mushrooms, grapes or strawberries.

In the case of a rupture portion which is ruptured during manufacture, the piece of cover foil may be connected at least to the cover rim at the same time as the cover rim is detached from the tray, but it is also possible to connect the piece of cover foil at least to the cover rim only after or before the cover rim and the tray are detached from each other and the relative movement is ended.

The relative movement of the cover rim and the tray, which is intended to separate the cover rim and the tray, wherein the breaking portion breaks, may be ended when the surface of the cover rim and the peripheral surface of the tray, which is located at the open side of the tray, are at substantially equal levels. When considering the tray in the above-described normal direction (in which the open side of the tray and the open side of the cover rim may be considered to be located at the upper side), the peripheral surface of the tray may be understood as representing, for example, an annular surface at the upper side of the tray. This is practical when the design of the package is chosen such that the lid edge and the tray have concentric upper surfaces, so that these upper surfaces can be brought to a substantially equal level, thereby obtaining a usable support surface for a portion of the piece of lid foil at the periphery of the piece of lid foil. In this case, a connection can be realized between the cover foil and at least the cover rim as desired. This does not alter the fact that the desired connection as described can also be established already in an earlier stage, as has been described in the foregoing.

In the case where the rupture portion has ruptured, it is desirable to have a secure connection between the tray, the lid edge and the piece of lid foil before the first use, in order to prevent accidental separation of the lid (i.e. the combination of the lid edge and the piece of lid foil) from the tray and to ensure that the interior space of the tray is permanently isolated from the outside, the piece of lid foil being connectable to the tray and the lid edge. In this case, a more secure connection between the piece of cover foil and the cover rim can be achieved than between the piece of cover foil and the tray, so that when the user separates the foil at first use, the piece of cover foil automatically separates from the tray but does not separate from the cover rim.

The limited relative movement of the cover rim and the tray to separate the cover rim and the tray from each other may be linear movement. This movement can be implemented in a simple manner. For example, in practical cases, the cover rim may be caused to move only a small amount downwards relative to the tray. Furthermore, this has the practical possibility of ending the relative movement of the cover rim and the tray when establishing the clamping connection between the cover rim and the tray. In this case, the manufacturing process of the package with established clamping connection according to the invention comprises the following steps: a package forming the tray, lid edge and rupture portion as a unit; forcing relative movement of the tray and the lid rim until they grip each other, wherein the rupturing portion ruptures; a piece of cover foil is provided and connected to at least the cover rim.

According to the above-described possibility of having an inward projection at least along a part of the circumference of the inner ring of the cover rim, there is no need to form further elements which are adapted to establish a clamping connection between the cover rim and the tray in the event of a relative movement of the cover rim and the tray. The cover rim may be moved over the tray until the projection of the cover rim reaches a position beyond the outer peripheral rim of the tray. When the package is made of plastic, it is sufficient to have the flexibility required in the process.

In order to establish a connection between the piece of cover foil and at least the cover rim, any suitable technique for allowing the two components to be connected to each other may be applied. For example, a local supply of heat may be provided so that the components, when in the position in question, are connected to each other as they melt. Means for supporting at least the cover rim during the connection between the piece of cover foil and at least the cover rim can advantageously be applied.

The package produced by the method according to the invention can be used for packaging various materials. As mentioned above, the food product is packaged, which is only one possibility. Typically, the material to be packaged is placed inside the tray before the piece of cover foil is attached at least to the cover rim.

The invention also relates to a package which can be manufactured by applying the above-mentioned method. Thus, according to a first aspect of the invention, with respect to a package, the package comprises: -a unitary tray having an open side and an annular cover rim at the open side of the tray and at an outer peripheral edge of the tray, and connected to the tray by a relatively weak breaking portion, the unitary being formed on the basis of a sheet, and wherein the cover rim has an inner ring in which an inward bulge is provided along at least a part of its periphery. Furthermore, the packaging can be completed by a piece of cover foil which is attached to the cover rim and seals the tray, wherein in practice there is material inside the tray.

According to a second aspect of the present invention, there is provided a package comprising: -a unitary tray having an open side and an annular cover rim, which cover rim is located at the open side of the tray and which cover rim is connected to the tray by a clamping connection, the unitary being formed on the basis of a sheet, wherein the cover rim and the tray are detached from each other, wherein the cover rim has an inner ring in which an inward bulge is provided along at least a part of its circumference, and wherein the bulge is located below an outer circumferential rim of the tray. The projection has the function of ensuring an effective clamping connection between the edge of the cover and the tray, as described hereinbefore.

The package as defined in the preceding paragraph can be further completed by the piece of cover foil being connected to at least the cover rim and sealing the tray, wherein, in practice, there is material within the tray. The surface of the cover rim and the peripheral surface of the tray at the open side of the tray may be at substantially equal levels. This is particularly advantageous with respect to an embodiment of the package in which the piece of cover foil is connected to the tray and the cover rim, wherein the piece of cover foil can be placed on the package in a planar manner. As mentioned above, by the bi-directional connection of the cover foil, it is advantageous when the connection between the piece of cover foil and the edge of the cover is stronger than the connection between the piece of cover foil and the tray, so that it is possible to ensure that the cover remains intact when the package is opened at the first time.

Furthermore, the invention relates to a mould for applying the above-mentioned method, i.e. a method for manufacturing a package, said package comprising: a one-piece tray having an open side and an annular cover rim at the open side of the tray and at an outer peripheral edge of the tray, the cover rim being connected to the tray by a relatively weak breaking portion, and the tray being formed on the basis of a sheet placed in a mould. In fact, the mould is adapted to allow the sheet to be forced to move in two different directions.

In a practical embodiment, the mould according to the invention comprises clamping means for clamping the sheet along the annular portion. Also, the mold may be adapted to form a cover rim having an inner ring with an inward projection disposed therein along at least a portion of a periphery of the inner ring. The mold may comprise a plurality of individual elements including: a first forming element having a forming surface shaped according to a bottom surface of the tray; and a second shaped element having a shaped surface shaped according to the upper surface of the edge of the cover, each of these elements being destined to be placed on the opposite side of the sheet. Furthermore, the die may comprise a movably arranged punching blade for enclosing the first forming element. This is advantageous when the punching blade is serrated, as previously described. Furthermore, the mould may comprise a pressure differential applying means for applying a pressure differential over the sheet, and may thus be suitable for vacuum forming or thermoforming sheets.

Drawings

The invention is explained in more detail on the basis of the following description of a method of manufacturing a package, wherein a sheet is manufactured in a mould as an integral tray and cover rim, in particular by deforming the sheet, with a relatively weak breaking portion therebetween, wherein the sheet is forced to move in two different directions, and wherein the tray is sealed by applying a piece of cover foil, which sealing may not be earlier than when the breaking portion breaks for the first time. Referring to the drawings wherein like reference numbers represent the same or similar elements and wherein:

figure 1 diagrammatically shows a cross-section of a package according to the invention;

FIG. 2 diagrammatically shows a top view of the package;

FIG. 3 diagrammatically shows a cross-section of a detail of the package;

FIG. 4 diagrammatically illustrates a portion of a rupture portion between a tray of the package and a lid edge;

FIG. 5 diagrammatically shows a cross-section of a portion of a mold and a cross-section of a portion of a sheet formed into a package by application of the mold, wherein the sheet is in an initial condition;

FIG. 6 diagrammatically shows a cross-section of a portion of a mold and a portion of a lamina, wherein the lamina is in a deformed condition;

figure 7 shows the manner in which a piece of cover foil is attached to the cover rim of the package;

FIG. 8 graphically illustrates a top view of a portion of a package having a potentially tearing lip at a lid edge of the package;

fig. 9 shows a detail of the package for the packaging situation, in which the rupture portion is ruptured and a detachable clamping connection is established between the tray and the lid edge; and

fig. 10 shows the way in which a piece of cover foil is connected to the tray and the cover rim in the packaged condition shown in fig. 9.

Detailed Description

Fig. 1 and 2 show a package 1 according to the invention, which in a preferred embodiment is made entirely of plastic, and which comprises: a unitary tray 10, a cover rim 20, and a relatively thin rupture portion 30 between the tray 10 and the cover rim 20. In the example shown, the tray 10 has a bottom 11 and an upstanding wall 12 extending from the bottom 11 and having a generally circular periphery. Within the framework of the invention, the tray 10 can have any shape, wherein the tray 10 has at least an open side 13. In the following description, the tray 10 assumes a normal orientation, i.e., an orientation in which the bottom 11 of the tray 10 is at the bottom and the open side 13 is at the upper side. At the open side 13, along the entire periphery, the tray 10 has a specially designed edge portion 14 with an upper surface 15, which is the peripheral surface of the tray 10, as can be clearly seen in the detail of the package 1 shown in fig. 3. The function of the edge portion 14 is elucidated hereinafter.

The cover rim 20 is ring-shaped and completely surrounds the tray 10 at the open side 13, wherein at the outer circumferential rim 16 of the tray 10 the cover rim 20 is fixedly connected to the tray 10. The shape of the periphery of the lid rim 20 is adapted to the shape of the periphery of the tray 10. Thus, the annular shape of the cover rim 20 may be circular, but may also be rectangular or square, for example, depending on the shape of the periphery of the tray 10. For the sake of completeness, it is noted that in case the terms "inner" and "outer" are used herein, these terms need to be understood as e.g. related to the central axis (symmetry axis) of the annular cap rim 20, wherein this position is closer to the inner part at a shorter radial distance from said axis, and wherein this position is closer to the outer part at a longer radial distance from said axis.

Between the cover rim 20 and the tray 10 there is a breaking portion 30. Fig. 4 shows that the breaking portion 30 may be perforated so that there may be an interconnection between the tray 10 and the cover rim 20 along the entire circumference of the tray 10 and the cover rim 20, but also a discontinuity 31 at a defined place. As a result, as described later, the action of rupturing the rupturing portion 30 requires a minimum amount of force.

The cover rim 20 has an inner ring 21 and an outer ring 22, in this example, having a stepped configuration. In the inner ring 21, there are inwardly directed projections. Within the framework of the invention, the projections 28 can be provided along the entire circumference of the inner ring 21, but the inner ring 21 can also have projections 28 at a plurality of defined positions. In the following, the function of the rings 21, 22 of the cover rim 20 and of the projections 28 in the inner ring 21 will be explained. As shown in the normal orientation of the entirety 1 of the tray 10 and the cover rim 20, the loops 21, 22 of the cover rim 20 extend in a generally vertically downward direction.

According to fig. 5 and 6, the manufacturing process of the package 1 is elucidated. In the example shown, the plastic foil 40 in the planar condition forms the basis of the package 1. A portion of this sheet 40 is shown in fig. 5 and 6. Furthermore, in said figures, a portion of the mould 41 can be seen, which portion is applied in the manufacturing process of the deformation of the sheet 40. The mould 41 comprises a first forming element 42 having a forming surface 43 shaped according to the bottom surface 17 of the tray 10. Furthermore, the mould 41 comprises a second forming element 44 having a forming surface 45 shaped according to the upper surface 23 of the cover rim 20. In the shaped surface 45 of the second shaped element 44, a groove 46 is provided for forming the bulge 28 in the inner ring 21 of the cover rim 20. Depending on the desired embodiment of the projections 28, the groove 46 may or may not be continuous along the entire circumference of the inner ring 21, along the entire circumference of the second forming element 44.

The first forming element 42 is surrounded by a movably arranged tubular punching blade 47. The first forming element 42 and the punching knife 47 are arranged concentrically with respect to each other. In the example shown, the punching knife 47 is movable in the vertical direction. In a general sense, the punching blade 47 is movable in the longitudinal direction of its tubular shape. On the functional side, i.e. the side facing the sheet 40 and used to obtain the defined interruptions 31 of the breaking portion 30, the punching blade 47 is serrated.

To form the sheet 40 into the package 1 as desired, the sheet 40 is prevented from being within the mold 41, with the first forming member 42 being located below the sheet 40 and the second forming member 44 being located above the sheet 40. Portions of the first forming element 42 and the second forming element 44 are located opposite each other so that by pressing the first forming element 42 and the second forming element 44 towards each other, for example in the example shown, by moving the first forming element 42 vertically upwards and the second forming element 44 vertically downwards, a ring-shaped portion of the sheet 40 can be clamped between the first forming element 42 and the second forming element 44. In the position in which the first forming element 42 and the second forming element 44 are pressed against each other with the sheet 40 in between, the relevant portion of the sheet 40 has formed the corresponding edge portion 14 of the tray 10 in the example shown. On the opposite side of this portion of the sheet 40, the other portion of the sheet 40 extends in an approximately horizontal direction in a planar state. This initial state of the sheet 40 is shown in fig. 5.

Under heated conditions, the sheet 40 is inserted into a mold 41. Subsequently, an overpressure is generated in two different directions inside the mould 41. At the location of the first forming member 42, the overpressure is mainly on the upper side of the foil 40, so that at this location a portion of the foil 40 is moved in a substantially downward direction towards and in contact with the forming surface 43 of the first forming member 42, as a result of which the tray 10 of the package 1 is obtained. On the other hand, the overpressure at the location of the second forming element 44 is mainly on the bottom surface of the sheet 40, so that at this location a portion of the sheet 40 moves in a substantially upward direction to and into contact with the forming surface 45 of the second forming element 44, as a result of which the cover edge 20 of the package 1 is obtained. In this process, the overpressure can also be mainly on the bottom side of the foil 40 at the location of the first forming element 42 and/or the overpressure can also be mainly on the upper side of the foil 40 at the location of the second forming element 44. The final condition of the sheet 40 is shown in fig. 6. It is noted that the process of deforming the sheet 40 is referred to as vacuum forming or thermoforming. In a manner known per se, in order to generate said overpressure and underpressure, respectively, the mould 41 may be provided with openings (not shown) at suitable locations, through which openings, respectively, for example compressed air may be introduced into the mould 41 and air may be sucked out through the openings in order to generate a vacuum. It is important that during the thermal process of the package 1, the portions of the first forming element 42 and the second forming element 44 facing each other are pressed firmly against each other to prevent leakage between the areas of the mould 41, which could lead to pressure being applied in different directions and the sheet being deformed, which could cause interference with the forming process.

The punching blade 47 is pressed in the sheet 40 in order to obtain a desired pattern of interruptions 31 at the location of the breaking portion 30. The purpose of the design of the first forming element 42 and the second forming element 44 is to provide the sheet 40 with a substantially U-shaped appearance at the location of the breaking portion 30, wherein in this case the breaking portion 30 is arranged in the base of the U. In particular, the U-shape has an upright orientation, which means that in this position the bottom surface of the lamella 40 is convex and the upper side of the lamella 40 is concave.

Once the sheet 40 is deformed and cut by the punch knife 47 in the manner described previously, the packet 1 is practically ready, in particular when the step for separating the packet 1 and the sheet 53 of the sheet 40 surrounding the lid edge 20 is carried out. This step can be performed in the die 41, wherein it can be performed simultaneously with the slitting action of the punching blade 47, in order to obtain a very efficient manufacturing process of the package 1. The separating step may be achieved by a punching process in which a punching tool (not shown) is applied and moved through the sheet 40 at the appropriate location for cutting at the appropriate location.

Once the package 1 has been formed, the next production step (shown in figure 7) can be carried out, preferably in the manner described previously. This next production step is intended to provide and arrange a piece of cover foil 60 for sealing the open side 13 of the tray 10 and forming the entire cover 24 together with the cover rim 20.

When the breaking portion 30 is intact, the upper surface 25 of the cover rim 20 extends at a higher level than the upper surface 15 of the rim portion 14 of the tray 10 in the mutual position in which the rim portion 14 of the tray 10 and the cover rim 20 are set with respect to each other. In this way, the upper surface 25 of the cover rim 20 can support the piece of cover foil 60 at the periphery. It is desirable to use this piece of cover foil 60 in this case: the piece of cover foil 60 is preferably only connected to the cover rim 20 along the entire circumference of the upper surface 25 of the cover rim 20. In so doing, sealing of the tray 10 is achieved and the cover 24 is also constructed, wherein there is a secure connection between the piece of cover foil 60 and the cover rim 20. This piece of cover foil 60 is at a higher level than the upper surface 15 of the rim portion 14 of the tray 10, which is advantageous in packaging food products (e.g. mushrooms, grapes or strawberries), because in this case the tray 10 can be filled all the way to the top once the contents are put in, without the cover foil 60 pressing on the contents.

A connection can be established between the piece of cover foil 60 and the cover rim 20 by local heating, so that the cover foil 60 is welded to the cover rim 20 at defined places. This can be done in a manner known per se by means of suitable tools 70, commonly referred to as sealing knives, a part of which is shown in fig. 7. The cover rim 20 may advantageously be supported during the joining process, and may also support the rim portion 14 of the tray 10. In this case, a suitable holder, which is movably arranged, may be applied for this purpose.

The assembly of tray 10 and cover 24 is designated for packaging materials (not shown) that are placed in tray 10 at any suitable time prior to application of the sheet of cover foil 60. In particular, the material may comprise a food product, such as the mushrooms, grapes or strawberries described above, and also, for example, salad, nuts, butter and other dairy products, such as yoghurt. The sealing of the tray 10 can be created in a protective environment or in other desired circumstances.

In the example shown, after the sheet of cover foil 60 is applied, the assembly of the tray 10 and the cover 24 is ready for first use. In the first use, a user grasps the cover rim 20 at a location on the stepped outer ring 22 and exerts a force on the cover rim 20 that is intended to rupture the rupturing portion 30 such that the inner peripheral edge 26 of the cover rim 20 separates from the outer peripheral edge 16 of the tray 10, and the cover 24 can then be removed from the tray 10. The cover rim 20 may have at least one tearing lip 27, as shown in fig. 8, which can be easily gripped by a user.

After the first use, the user can close the tray 10 again by placing the cover 24 back on the tray 10 and applying a slight downward pressure in the process, wherein a clamping connection can be established between the cover 24 and the tray 10. In fig. 9, a possible mutual position of the tray 10 and the cover rim 20 in this case is shown. In this position, the cover rim 20 engages with the rim portion 14 of the tray 10, wherein the inner peripheral rim 26 of the cover rim 20 cannot move beyond the outer peripheral rim 16 of the tray 10 in the vertical direction due to the clamping action between the higher part of the inner ring 21 of the cover rim 20 and the outer peripheral rim 16 of the tray 10, as shown. The following steps may be repeated as often as desired, depending on preference: the tray 10 is reopened by breaking the clamping connection and removing the cover 24, and the tray 10 is reclosed by placing the cover 24 in place on the tray 10 and establishing the clamping connection.

The projections 28 in the inner ring 21 of the cover rim 20 have the function of establishing a clamping connection, wherein the cover rim 20 at the location of its upper surface 23 of the inner ring 21 is centered with the rim portion 14 of the tray 10, and wherein an incorrect placement of the cover rim 20 is prevented and a complete sealing of the tray 10 is achieved, which can easily be broken again. With the clamping connection between the tray 10 and the cover rim 20 in fact, the outer peripheral rim 16 of the tray 10 lies directly above the projection 28. There is no need to redesign the package 1 to be able to have additional aspects of the clip connection (e.g. projections, grooves, etc.). In contrast, the outer peripheral edge 16 of the tray 10 and the inner ring 21 of the cover rim 20, which are at a level directly above the bulge 28, are automatically adapted to be clamped against each other after the breaking portion 30 has been broken. By pressing the cover rim 20 downwards on the tray 10, a clamping connection is established, wherein at least the inner ring 21 of the cover rim 20 springs inwards to a certain extent and is in contact with the outer circumferential rim 16 of the tray 10. For reinforcement purposes, the inner ring 21 may be designed in such a way that the outer peripheral edge defines a tapered inner space, in the example shown, tapering to a ledge and including the ledge 28. To disengage the clip connection, a user may grasp a portion of the lid rim 20 at the outer ring 22 in the first example and use that portion to tilt the inner ring 21 away from the outer peripheral edge 16 of the tray 10.

As an alternative to applying a piece of cover foil 60 in the package 1 in order to seal the tray 10 as described above, the cover rim 20 may first be placed in a lower level with respect to the tray 10, wherein the breaking portion 30 is broken, in order to obtain a mutual position of the cover rim 20 and the tray 10, i.e. a mutual position in which the upper surface 15 of the rim portion 14 of the tray 10 and the upper surface 25 of the cover rim 20 are at substantially the same level, as shown in fig. 9. Hereinafter, a manner of further implementing the process in this case is described.

In a first step, a downward pressure is exerted on the cover rim 20, wherein the rupture portion 30 is completely ruptured, as a result of which the cover rim 20 is separated from the tray 10. At some point during the downward movement of the cover rim 20, a clamping connection is established between the cover rim 20 and the tray 10 as previously described. The downward movement is stopped when the upper surface 15 of the rim portion 14 of the tray 10 and the upper surface 25 of the cover rim 20 are at substantially the same level. At this point, the next production step may be performed, as shown in fig. 10. The next production step is intended to provide and apply a sheet of cover foil 60 for sealing the open end 13 of the tray 10 and for constituting the entire cover 24 together with the cover rim 20.

Since the upper surface 15 of the rim portion 14 of the tray 10 and the upper surface 25 of the cover rim 20 extend at substantially the same level, the upper surfaces 15, 25 may support the piece of cover foil 60 over the entire circumference. In the example shown, the piece of cover foil 60 is connected to the package 1 in two places, namely along the entire circumference to the upper surface 15 of the rim portion 14 of the tray 10 and also along the entire circumference to the upper surface 25 of the cover rim 20. As a result, a tray 10 sealed in an airtight manner is obtained and also a cover 24 is constructed, wherein there is a firm connection between the piece of cover foil 60 and the cover rim 20.

It is possible to attach the piece of cover foil 60 to the upper surface 25 of the cover rim 20 at an earlier stage. This may even occur during a relative movement between the tray 10 and the cover rim 20, which relative movement serves to achieve a clamping connection and to place the above-mentioned upper surfaces 15, 25 at substantially equal levels. In this case, there is an advantage in that the manufacturing process can be faster and it can be ensured that the cover rim 20 does not move beyond a desired position relative to the rim portion 14 of the tray 10. The connection between the piece of cover foil 60 and the tray 10 may generally be less secure (and may generally be peelable with a higher degree of force) than the connection between the piece of cover foil 60 and the cover rim 20. In this case, it takes more time to establish the latter connection than to establish the first connection. In this case, the connection requiring more time is already established during the relative movement of the tray 10 and the cover rim 20, which may at least partly save time and, as a result, the manufacturing process may be less costly. For the sake of completeness, it is noted that it is more practical to establish a connection between the piece of cover foil 60 and the cover rim 20 at a higher temperature than the connection between the piece of cover foil 60 and the tray 10.

In accordance with the above, the local heat supply makes it possible to form a connection between the piece of cover foil 60 and the tray 10 and the cover rim 20, so that the cover foil 60 is welded to the tray 10 and the cover rim 20 at defined places. This can be carried out in a manner known per se by means of a suitable tool 70, a part of which is shown diagrammatically in fig. 10. The cover rim 20 may advantageously be supported during the joining process, and may also support the rim portion 14 of the tray 10. In this case, a suitable holder, which is movably arranged, may be used for this purpose.

With regard to the use of the cover foil 60 in case the rupture portion 30 has ruptured, it is possible to choose to establish a connection only between the cover foil 60 and the cover rim 20. In addition to this, it is indeed not necessary to have a connection along the entire circumference, with reference to this connection and the possible connection between the cover foil 60 and the rim portion 14 of the tray 10. However, in view of the desire to obtain a strong cover 24, wherein the cover rim 20 and the piece of cover foil 60 cannot easily be pulled away from each other, a complete connection between the piece of cover foil 60 and the cover rim 20 is preferred. In general, the location where the connection needs to be established may in fact be determined as desired, wherein it is important to take into account that it may be desirable to completely seal the interior space of the tray 10.

In the example shown, the assembly of tray 10 and cover 24 is ready for a first use after the desired connection is made. In said first use, the user grips the cover rim 20 at the outer ring 22, breaks the clamping connection between the cover rim 20 and the tray 10, and pulls the cover 24 from the tray 10, wherein the connection between the cover foil 60 and the tray 10 is broken, while the connection between the cover foil 60 and the cover rim 20 remains intact. In the manufacture of the assembly, when the piece of cover foil 60 is connected to both the tray 10 and the cover rim 20, as described above, it can be chosen to make the connection to the tray 10 less secure than to the cover rim 20 (peelable under a higher degree of force), so as to ensure that the connection between the piece of cover foil 60 and the tray 10 is only broken.

The above-mentioned important advantages of the assembly of the tray 10 and the cover 24 and the manner of manufacturing thereof are summarized below.

The assembly is suitable for packaging food products that need to be packaged in an airtight manner before the first use, since the connection between the piece of cover foil 60 and the tray 10 can be established along the entire circumference;

in order to seal the tray 10 before first use, no separate cover foil is required which no longer has a function after first use, unlike in many common cases. As a result, the assembly is more environmentally friendly. Since the piece of cover foil 60 is integrated in the cover 24, a comparatively light cover 24 is obtained, saving material;

the tray 10 and the lid rim 20 as part of the lid 24 can be manufactured in a relatively simple and inexpensive manner by vacuum forming or thermoforming starting with a planar sheet 40 and using a mould 41. After breaking the relatively thin breaking portion 30 between the tray 10 and the cover rim 20, it is possible to locate the cover rim 20 directly in the correct position with respect to the tray 10. The cover 24 need not have a separate manufacturing process and no additional steps are required to position the cover 24 on the tray 10;

the assembly can be easily handled by a user, wherein the cover 24 can easily be pulled away from the tray 10 at the first use, and wherein the clamping connection can easily be repeatedly established or broken between the cover 24 and the tray 10 at further use.

It will be clear to a person skilled in the art that the scope of the present invention is not limited to the examples discussed in the foregoing, but that the invention is capable of numerous variations and modifications without departing from the scope of the invention as defined in the appending claims.

With respect to the piece of cover foil 60, it is noted that the cover foil may be made of any suitable material, e.g. plastic or aluminum. Furthermore, the piece of cover foil 60 may be provided with an imprint, e.g. for information purposes and/or advertising purposes.

With regard to the term "punching knife" used in the foregoing, it is noted that within the framework of the present invention, a broad understanding is required, i.e. to be able to locally realize one or more interruptions or at least weakened tools. Instead of a single tubular punching knife 47, a combination knife can also be applied. With regard to each of the forming elements 42, 44 of the mould 41, the forming elements 42, 44 may, if desired, indeed be constituted by two or more blocks in a manner known per se, wherein, in so doing, in practice, assuming such a configuration, one or more such blocks may be slidably arranged so as to be able to, or at least facilitate, the release of the package 1 from the mould 41.

The cover rim 20 does not have to be formed with both an inner ring 21 and an outer ring 22. In view of the desired possibility of clamping the cover rim 20 on the tray 10, this is advantageous when the cover rim 20 is formed with at least an inner ring 21, wherein in this case there may also be a projection 28 which, in combination with the clamping connection, ensures correct positioning of the cover rim 20 relative to the tray 10, without the user of the package 1 having to pay particular attention to the positioning.

The fact that the process of vacuum forming or thermoforming can be performed from two different directions and that the bulge 28 can be obtained in the inner ring 21 of the cover rim 20 can be applied independently of each other. Accordingly, the present invention also relates to a method of manufacturing a package 1 comprising: a one-piece tray 10 having an open side 13 and an annular cover rim 20 which is located at the open side 13 of the tray 10 and at an outer circumferential rim 16 of the tray 10 and which is connected to the tray 10 by means of a relatively weak breaking portion 30, wherein a mould 41 is provided, wherein a sheet 40 is provided and placed in the mould 41, and wherein the cover rim 20 is formed with an inner ring 21, wherein along at least a part of its circumference an inward bulge 28 is obtained. The invention therefore further relates to a mould 41, for the purpose of applying the method for manufacturing a package 1 comprising: an integral tray 10 having an open side 13; and an annular cover rim 20 located at the open side 13 of the tray 10, on the outer peripheral rim 16 of the tray 10, and connected to the tray 10 by a relatively weak breaking portion 30 according to a sheet 40 placed in a mould 41, wherein the mould 41 is adapted to form an inner ring 21 for the cover rim 20 and to realize an inward bulge 28 therein along at least a part of its periphery. In particular, the mould may comprise a shaping element 44 having a shaping surface 45 with grooves 46 for forming said projections 28.

The present invention can be summarized as follows. The package 1 comprises: a one-piece tray 10 having an open side 13 and an annular cover rim 20 at the open side 13 of the tray 10 and at an outer peripheral rim 16 of the tray 10, and connected to the tray 10 by a relatively weak breaking portion 30. For manufacturing the package 1, a mould 41 with a plurality of separate elements 42, 44, 47 is provided. Furthermore, a sheet 40 is provided and placed in a mould 41, wherein the sheet 40 is forced to move in two different directions in order to shape the sheet 40 into a package 1 having a tray 10 and a cover rim 20. By applying a punching blade 47, the foil 40 is slit in order to obtain the ruptured portion 30 of the package 1. Moreover, the package 1 is separated from the surrounding material 53 of the sheet 40. Furthermore, a piece of cover foil 60 is provided and is connected to at least the cover rim 20.

The rupture portion 30 may be broken prior to application of the sheet of lid foil 60, but this is not essential. In any case, the cover rim 20 and the tray 10 are preferably adapted to be arranged to engage each other by means of a clamping connection after the cover rim and the tray are no longer integrally formed with each other by means of the breaking portion 30. The cover rim 20 may be formed with an inner ring 21 in which an inward bulge 28 is obtained along at least a part of its periphery, which assists in establishing a clamping connection between the cover rim 20 and the tray 10 once the cover rim 20 is broken and detached from the tray 10, wherein a correct positioning of the cover rim 20 on the tray 10 is ensured.

Claims (20)

1. A method of manufacturing a package (1) comprising an integral tray (10) having an open side (13) and an annular cover rim (20) which is located at the open side (13) of the tray (10) and at an outer circumferential rim (16) of the tray (10) and which is connected to the tray (10) by a relatively weak breaking portion (30), wherein a mould (41) is provided, wherein a sheet (40) is provided and placed in the mould (41), in which mould the sheet (40) is forced to move in two different directions for forming the sheet (40) into the package (1) having the tray (10) and the cover rim (20), wherein the sheet (40) is clamped along an annular portion, wherein a portion of the sheet (40) located inside the ring-shaped portion and a portion of the sheet (40) located outside the ring-shaped portion move in the two different directions, and wherein the desired shaping movement of the sheet (40) in the mould (41) is achieved by applying a pressure difference in the mould (41) over the sheet (40) in the two different directions.

2. A method according to claim 1, wherein the sheet (40) is forced to move in the two different directions simultaneously.

3. Method according to claim 1 or 2, wherein the cover rim (20) is formed with an inner ring (21) in which an inward bulge (28) is provided along at least a part of the circumference of the inner ring.

4. Method according to claim 1 or 2, wherein the mould (41) comprises a plurality of separate elements (42, 44, 47) comprising: a first forming element (42) having a forming surface (43) shaped according to a bottom face (17) of the tray (10); and a second forming element (44) having a forming surface (45) shaped according to an upper surface (23) of the cover rim (20), wherein, upon placing the sheet (40) in the mould (41), the first forming element (42) is located on one side of the sheet (40) and the second forming element (44) is located on the other side of the sheet (40), wherein the sheet (40) is clamped between mutually facing portions of the first and second forming elements (42, 44), wherein the first forming element (42) is surrounded by a movably arranged tubular punching knife (47), wherein the mutually facing portions of the first and second forming elements (42, 44) clamped between them are located opposite the sheet (40), -forcing the movement of the sheet (40) in two opposite directions, so as to bring a first portion of the sheet (40) into contact with the forming surface (43) of the first forming element (42) and thus constitute the tray (10), and a second portion of the sheet (40) into contact with the forming surface (45) of the second forming element (44) and thus constitute the cover edge (20), and wherein the punching knife (47) is moved in the direction of the sheet (40) and is partially pressed into the sheet (40) to obtain the breaking portion (30) between the tray (10) and the cover edge (20).

5. Method according to claim 4, wherein the weaker and less weak parts of the breaking portion (30) are obtained by applying a serrated punching knife (47).

6. Method according to claim 4, wherein an opening (31) is obtained at a defined position between the tray (10) and the cover rim (20) by applying the punching blade (47).

7. Method according to claim 4, wherein the package (1) is separated from the surrounding material of the sheet (40), and wherein the movement of the punching blade (47) within the sheet (40) is performed simultaneously.

8. A method according to claim 1 or 2, wherein the sheet (40) is heated before shaping the sheet (40).

9. Method according to claim 1 or 2, wherein a piece of cover foil (60) is provided and attached to the cover rim (20) for sealing the tray (10).

10. Method according to claim 1 or 2, wherein the cover rim (20) and the tray (10) are separated from each other by forcing the cover rim (20) and the tray (10) to a limited mutual movement, wherein the breaking portion (30) is broken, wherein a clamping connection is established between the cover rim (20) and the tray (10), and wherein a piece of cover foil (60) is provided and connected at least to the cover rim (20) for sealing the tray (10).

11. Method according to claim 10, wherein the cover foil (60) is connected at least to the cover rim (20) during the mutual movement of the cover rim (20) and the tray (10).

12. Method according to claim 10, wherein the mutual movement of the cover rim (20) and the tray (10) ends when a surface (25) of the cover rim (20) and a peripheral surface (15) of the tray (10) at the open side (13) of the tray (10) are at a practically equal level.

13. Method according to claim 10, wherein the cover foil (60) is connected to both the tray (10) and the cover rim (20).

14. Method for manufacturing a package (1) comprising an integral tray (10) having an open side (13) and an annular cover rim (20) which is located at the open side (13) of the tray (10) and at an outer circumferential rim (16) of the tray (10) and which is connected to the tray (10) by a relatively weak breaking portion (30), wherein a mould (41) is provided, wherein a sheet (40) is provided and placed inside the mould (41), in which mould the sheet (40) is forced to move in two different directions for forming the sheet (40) into the package (1) with the tray (10) and the cover rim (20), and wherein the cover rim (20) is formed with an inner ring (21), an inward projection (28) is provided in the inner ring along at least a portion of the circumference of the inner ring.

15. A mould (41) for applying a method of manufacturing a package (1) comprising a unitary tray (10) having an open side (13) and an annular cover rim (20) at the open side (13) of the tray (10) and at an outer circumferential rim (16) of the tray (10) and connected to the tray (10) by a relatively weak breaking portion (30), the unitary body being formed on the basis of a sheet (40) placed in the mould (41), wherein the mould (41) is adapted to allow the sheet (40) to be forced to move in two different directions for forming the sheet (40) into the package (1) having the tray (10) and the cover rim (20), wherein the mould comprises clamping means (42, 44) for clamping the sheet (40) along an annular portion, and wherein the mould (41) comprises pressure applying means for applying a pressure difference in two different directions over the sheet (40).

16. A mould (41) according to claim 15, adapted to form the cover rim (20) with an inner ring (21) in which an inward bulge (28) is provided along at least a part of its circumference.

17. A mould (41) according to claim 15 or 16, comprising a plurality of separate elements (42, 44, 47) comprising: a first forming element (42) having a forming surface (43) shaped according to a bottom face (17) of the tray (10); and a second forming element (44) having a forming surface (45) shaped according to an upper surface (23) of the cover rim (20), each of said first and second forming elements being destined to be placed at opposite sides of the sheet (40).

18. A die (41) according to claim 17, comprising a tubular punching blade (47) movably arranged to enclose the first forming element (42).

19. The die (41) according to claim 18, wherein the punching blade (47) is serrated.

20. A mould (41) for applying a method of manufacturing a package (1) comprising: -a unitary tray (10) having an open side (13) and an annular cover rim (20) located at the open side (13) of the tray (10) and at an outer circumferential rim (16) of the tray (10) and connected to the tray (10) by a relatively weak breaking portion (30), the unitary being formed on the basis of a sheet (40) placed in a mould (41), wherein the mould (41) is adapted to allow a forced movement of the sheet (40) in two different directions for forming the sheet (40) into the package (1) having the tray (10) and the cover rim (20), and wherein the mould (41) is adapted to form the cover rim (20) with an inner ring (21) in which an inward bulge (28) is provided along at least a part of its circumference .