EP0773894A1

EP0773894A1 - Container with opening means, making thereof and tool for making container

Info

Publication number: EP0773894A1
Application number: EP95926844A
Authority: EP
Inventors: Jorn Jensen
Original assignee: ANDERSEN Irma
Current assignee: ANDERSEN Irma
Priority date: 1994-08-05
Filing date: 1995-07-13
Publication date: 1997-05-21
Also published as: NO970481D0; AU3108695A; FI970284A0; WO1996004187A1; NO970481L; FI970284A; DK91494A; AU691949B2; CA2196428A1

Abstract

A packing (1) for e.g. meat consists of a tray (2), which is produced of a relatively rigid plastic foil, and a closure (3) of a relatively flexible plastic foil. The tray (2) has a bottom (4), a side wall (5) and a rim (6). The foil of the closure (3) is heat sealed on the rim (6) of the tray (2) when the tray (2) is filled with the product to be packed. For easily being able to open the packing the foil of the tray is formed with a point (13) situated at the closure plane for penetrating the foil of the closure (3). When the foil (3) initially has been penetrated it is easy to remove by inserting, by way of example, a finger through the formed opening in the foil (3) and tearing this up. The penetrating point (13) is surrounded of a ringformed depression (14) in the foil having an outer wall (15), which is merging into the remaining tray (2), an inner wall (16), which is merging into the penetrating point (13), and a bottom (17), which is connecting the two walls (15; 16). By a pressure with a finger on the underside of the bottom (17) of the depression (14), the depression (14) is deformed by which the point (13) is driven through the foil of the closure (3).

Description

CONTAINER WITH OPENING MEANS, MAKING THEREOF AND TOOL FOR MAKING CONTAINER

The invention concerns a packing for e.g. meat including a tray produced of a relatively rigid plastic foil and having a bottom- and side wall and a plane closure of a relatively flexible plastic foil for heat sealing on the tray.

Packings of this type is used to a great extent for distribu¬ tion of foodstuffs. The packings are cheap to produce and convenient to use in the stage of packing. At the same time they offer the foodstuffs a good protection against external contamination and they can therefore freely be lying about, by way of example, in a refrigerating showcase of a supermarket where the consumer can subject the displayed products to a direct inspection before buying, as the closure usually consists of a transparent plastic foil.

The packings are, in addition, normally tight, such as the consumer can carry the bought products home without risk for being contaminated, by way of example, exuding meat juice.

When the consumer is going to open a packing for using the packed product problems arise, however, with the conventional packings of this type.

The closure need namely, for safely being able to protect the product, to be heat sealed onto the tray with a sufficiently large specific strength there normally is between 5.000 and 10.000 g/25mm. With this strength it will be almost impossible to pull off the closure of the tray, even if the closure for this object should be equipped with a tear-off flap. The specific strength must be as low as between about 5 and 15% of the above named strength if the packing should be suitable for being opened by pulling off the closure.

The heat sealing such must have a small specific strength if the closure should be easy to pull off, and a large strength if the packing should be sufficiently reliable. In the most majority of cases the packing industry will, however, first of all make a point of that the packing is reliable. The decisive economic consideration in this connection is that the packing should be able to secure the durability of the packed products. If the packing is becoming not tight it will, as a rule, cause the packed products to be rejected by which a large economic loss can arise. Therefore there is used, almost solely, packings having such a large specific strength of heat sealing that the closure cannot be pulled off. Instead the consumer has to open the packing by initially penetrating the closure with a sharp-pointed tool and subsequently tearing up the broken plastic foil .

The plastic foil of the closure consists, however, usually of a material as is difficult to penetrate and as therefore requires a tool having a relatively sharp point as always is on the tools, e.g. knifes or scissors, as the consumer immediately has to his disposal. The penetrating operation is in addition not quite harmless. Such there is always a risk for that the sharp-pointed tool by accident can hit a hand holding on to the packing. In addition the consumer especially often sticks the tool down in the packing with such a large force that not only the foil of the closure is penetrated but also that the tool is deeply forced into the packed product as could thereby be more and less damaged. Often the consumer, in excess of the time spended for the proper process of opening, in addition afterwards also need to spend time for cleaning-up the used tool.

Concerning remedying these drawbacks there is developed a packing provided with a built-in tool for breaking through the plastic foil of the closure. This packing is described in the European patent application No. 0 330 812. The tool consists, in this case, of a small about 0.4 mm thick, relatively rigid polyvinylidenchloride (PVC) plate as behind a bending line is glued together with the closure. On the other side of the bending line the PVC plate is free and on this side there is a V-formed weakening line.

when the packing is going to be opened the free side of the PVC plate initially is lifted a little upwards after which the V-formede weakening line is broken by pressing out the material within the weakening line. Thereby is formed a triangular point as is pressed down into the plastic foil of the closure for penetrating this. Finally the plastic foil is teared up merging from the now formed hole.

This solution is remedying some of the above named drawbacks but in return the construction is expensive to produce and troublesome to work with.

Therefore there is a need for a packing of the type stated in the opening paragraph as is reliable for packing of even perishable foodstuffs, is easy to open without use of auxiliary tools, and still is cheap to produce.

This is, according to the invention, obtained by forming the foil of the tray with a point situated at the closure plane for penetrating the foil of the closure. By means of this construction it is possible to use secure packings having a high strength of heat sealing, as the foil of the closure now, without using auxiliary tools, can be broken merely by a pressure for manually to deforming the packing or parts of this such that the point is forced through the foil of the closure. The point does not increase the total production cost of the packing in relation to conventional packings of this type as the point is formed in the same operation as the tray in its entirety and without using more material than else. The point simply is drawn out of the foil material as thereby at this place is becoming somewhat thinner and at the same time more hard. This increasing of the hardness is imparting to the foil the necessary strength for being able to penetrating the foil of the closure.

In a preferably embodiment the penetrating point can be surrounded of a ring-formed depression in the foil with an outer wall merging into the other tray, an inner wall merging into the penetrating point, and a bottom connecting the two walls. The point is to be directed against and placed relatively close below the foil of the closure as is penetrated when the point is lifted by e.g. with a finger to act on the bottom of the depression with a sufficiently large upwards directed pressure to deforming both this and the outer wall. hen the point initially has penetrated the foil of the closure the consumer easily can tear the foil up by sticking a finger down through the now formed opening in the foil and pulling it free along the rim of the tray.

For being able easily to lift the point the bottom of the depression can in section be semicircular. Thereby the foil in the outer wall and the bottom will roll, such offering relatively small resistance against being deformed.

When the bottom of the depression is in a conical surface converging against the bottom of the tray and relatively sharp merges into the two walls of this, the point can easily be lifted with a finger clapping the bottom into the depression.

In an appropriate elaboration of this construction the bottom leaps back elastically to its original position when the pressure comes to an end, by which the point anew is pulled down into the depression. This is an advantage as the point not is in the way of the finger as finally are going to tear the foil of the closure totally up.

in a preferable embodiment the outer wall of the depression is bellow-formed, by which the depression becomes particularly easy to deform and the consumer therefore only need to exercise a small pressure with the finger for being able to lift the point and penetrate the foil of the closure. This solution is particularly expedient as the packing also are convenient to open for persons having weak fingers.

When using the last-mentioned embodiment the bellow can have a symmetrical wave pattern by which the point will penetrate the foil of the closure in a direction perpendicular to this.

The bellow can, however, also have an asymmetric wave-pattern, and in this case the point will not merely prick a hole in the foil of the closure, but via a shearing movement in the foil b terminating at the outer wall instead of remain standing in the middle of the depression. Thereby is obtained the advantage that the foil of the closure is opened effectively as there instead of a small hole is formed a tear as the finger easily can be sticked through when the foil finally is going to be teared totally up. Another advantage consists in that the point is brought out of way such as the consumer is not sticking himself when the finger via the tear is stucked down into the opening of the depression for removing the foil.

For further securing the consumer against sticking himself on the point the contour of the depression can at the transition to the remaining tray delimit an opening having a wide section allowing a finger to be inserted and a narrow section not allowing this. This device is especially expedient in connection with a depression having an asymmetric bellow as the point during penetrating of the foil of the closure is brought into a final position in the narrow section where the finger of the consumer is not able tc get into.

A further measure of precaution for protecting the consumer against sticking himself on the point consists in letting the penetrating point stepwise merging into the inner wall of the depression and having a height as corresponds to the thickness of the foil of the closure or merely is somewhat larger than this thickness.

As the used closure foil usually is thinner than the epidermis of a finger such a point can very well penetrate the foil but not wound the consumer by penetrating the epidermis.

In the above named examples the point has in all cases been placed in a deformable area of the tray, instead can the point be formed in a stiff area of e.g. the side wall of the tray close to the closure foil as then can be penetrated by pressing the flexible foil down the stationary point.

The invention also concerns a method for producing a packing according to the invention by which the tray is vacuum-formed in a matrices with a sprig formed, in the main, as the inner side of the penetrating point.

The invention further concerns a tool for carrying out the method by which the sprig of the matrices consists of an outer sprig and of an inner sprig arranged in a central through-going hole in the outer sprig, and the through-going hole and the inner sprig are formed in a such a way in the transverse direction that there between the inner sprig and the through-going hole is left at least one air slit extending downwards from the over side of the outer sprig to the underside of this and communicating with the source of vacuum. Thereby securing that the air below the penetrating point is completely evacuated during the vacuum forming process and that the point thereby becomes sufficiently sharp.

The invention will be explained more fully by the following description of embodiments, given by way of example, with reference to the drawing, in which fig. l shows in perspective, seen oblique from above, a first embodiment for a packing according invention,

fig. 2 shows the same, but seen oblique from below in perspective,

fig. 3 shows in perspective, seen oblique from above, another embodiment for a packing according invention,

fig. 4 shows a section of the packing of fig. l and 2,

fig. 5 a,b,c show fragmentarily, in a larger scale, a section through a first embodiment of a device for perforating the cover foil of the packing, seen in three successive process-stages,

fig. 6 shows fragmentarily, seen from above in a larger scale, another embodiment for a device for perforating the cover foil of the packing,

fig. 7 a,b,c is a section taken along the line VII - VII in fig. 6, showed in three successive process-stages of the showed device for perforating the cover foil of the packing ,

fig. 8 shows fragmentarily, seen from above in a larger scale, a third embodiment for a device for perforating the cover foil of the packing,

fig. 9 a,b,c,d,e is a section, taken along the line IX - IX in fig. 8, in five successive proces-stages of the showed device for perforating the cover foil of the packing,

fig. 10 shows fragmentarily, seen from above in a larger scale, a fourth embodiment for a device for perforating the cover foil of the packing, fig. 11 a,b,c shows a section, taken along the line XI - XI in fig. 10, in three successive proces-stages of the showed device for perforating the cover foil of the packing ,

fig. 12 shows fragmentarily in section a fifth embodiment for a device for perforating the cover foil of the packing ,

fig. 13 shows the same, but seen from above,

fig. 14 a,b shows fragmentarily in section the device of fig. 12 and 13 for perforating the cover foil of the packing, in two successive proces-stages,

fig. 15 shows in a larger scale a fragment of a device for perforating the cover foil of the packing with a perforating sprig,

fig. 16 shows a section of a tool for forming a tray for the packing according invention,

fig. 17 is a lateral view of a sprig for the tool of fig. 16,

fig. 18 is a top view of the same,

fig. 19 shows a section through a sprig corresponding to the sprig of fig. 17, but having a triangular section,

fig. 20 shows a matrices for the tool of fig. 16, but in another embodiment for a forming sprig,

fig. 21 is a top view of the forming sprig of fig. 20,

fig. 22 shows the forming sprig of fig. 20, seen from below,

fig. 23 shows in a larger scale, a section of the second embodiment for the forming sprig, seen from above, and fig. 24 is a lateral sectional view of the same.

Fig. 1 and 2 shows in perspective, seen oblique from above and from below, respectively, a first embodiment for a packing according invention. The packing, which is generally designated by 1, consists of a rectangular tray 2 and a closure 3.

The tray 2 has a bottom 4 (fig. 2), a side wall 5 and a rim 6. It is produced of a relatively heavy thermoplastic, e.g. polyvinylidenchloride, polyethylenterephthalate or polystyrene in thicknesses as typically could be between 250 and 600 my.

The material can be either in form of a monofoil or be laminated with polyethylene or polypropylene. The tray is produced by initially heating the foil and then forming this in a matrices by means of vacuum and possibly of compressed air to the wanted form.

The closure 3 also consists of a thermoplastic foil which typical can be in form of a laminate of polyamide/polyethylene or polyethylenterephthalate/polyethylene or similar in thicknesses which typically can be between about 40 and 60 my. The material will usually be fairly flexible.

In the filled and closed packing the foil of the closure is heat sealed on the rim 6 of the tray. For being able to controlling the foil of the closure during this process the basis of this (polyamid or polyethylenterephthalat) must be oriented and preferably biaxially oriented. This is obtained by stretching the foil in the longitudinal and transverse direction followed of a fixing by means of a heat shock.

This structure secures that the foil of the closure not elongates when acted on by the heat from the heat sealing during the heat sealing process. Moreover the molecule structure of the plastic will change from having a tangled and branching molecular structure to having straight rows of molecular chains arranged parallel in the longitudinal direction.

Fig. 3 shows another embodiment for a packing according invention. This packing, which is generally designated by 7, consists of a round tray 8 and a round closure 9. The tray has a bottom 10, a side wall 11 and a rim 12. The used plastic materials are the same as used for the first embodiment of fig. l and 2.

Both embodiments are typically used for food stuffs, e.g. meat, and they are therefore closed by a heat sealing which has a large specific strength for securing the filled packing against becoming not tight and the contents becoming tainted.

The foil of the closure therefore cannot or can only with most difficulty be pulled off the tray when the consumer is going to open the packing and using the contents. Instead he have to try tearing it to pieces, but this causes immediate trouble as the material is ductile and hard to penetrate.

As showed in fig. 1 and 2 the packing according to the invention is, however, equipped with a point 13 serving to penetrate the foil of the closure 3. hen such a penetrating has taken place the particular molecular structure of the foil will cause it to burst linear along a molecular chain. Thereby an opening arises in the foil of the closure sufficiently large for introducing a finger by which the foil easily can be teared up and removed along the rim of the tray. The packing such has been opened rapidly and easily and the consumer has obtained full access to the contents of the packing without using any form for auxiliary tools. The point constitutes an integral part of the tray and is produced contemporary with this and without using extra materials. The point therefore in no way is increasing the cost of the packing and it is immediately to hand when the packing is going to be opened.

The decisive operation in the opening process is the perforating of the foil of the closure as takes place by deforming the packing or part of this in such a way that the point is brought past the closure plan of the packing, or in other words, is forced through the foil of the closure. For this purpose can the tray be formed in different ways which can facilitate and control this operation, such as it will be described more detailed by means of the following examples with reference to figures where identical parts has been designated by the same reference numbers.

In fig. ι and 2 the tray is equipped with a special device for perforating the foil of the closure. This device is called a perforator below and is in fig. l and 2 generally designated by 14. The perforator can also be seen in fig. 4 showing in section the pespectively showed packing of fig. l and 2.

The perforator 14 has form of a ringformed depression in the plastic foil of the tray and consists in the main of a ringformed outer wall 15, a ringformed inner wall 16 and a ringformed bottom 17 connecting the two walls 15 and 16.

In the showed first embodiment of the packing the perforator is arranged in an incision 18 in one of the corners of the rectangular tray. The incision is formed by in this corner to leading the side wall 11 inwards into an about half conical surface. The incision protects the perforator against being activated by accidentally outer influences which unintentional could cause the point to perforating the foil of the closure. The incision is, however, open below, therefore allowing the consumer having full access to deform the perforator with a finger.

The outer wall 15 partly merges into the rim 6 of the tray, partly in a ledge 19, the level of which is situated a little below the rim 6 and is terminating, above at the top, the conical surface of the incision 18. The inner wall 16 of the perforator merges into the point 13 which remain standing in a small distance below the foil of the closure 3. When the bottom 17 of the perforator therefore is acted on by a sufficiently large upwards directed pressure the perforator will deform and the point being lifted up and penetrating the foil of the closure.

The walls of the perforator can, however, very well be fairly stiff and in these cases it can be troublesome to deform the perforator. If the bottom 17 of the perforator, seen in section, is mainly semicircular, however, as showed in fig. 4, it will be easy to deform the perforator as the outer wall 15 in this elaboration is inclined to roll inward along the circle of the bottom 17 without encountering much resistance when the perforator is exposed to a upwards directed pressure.

In fig. 1,2 and 3 the perforator is arranged in a corner of the rectangular tray 2. The perforator can, however, be arranged in other suitable places in a tray and function in exactly the same way. By way of example, the perforator can be arranged at a side or free in the bottom of the tray.

in fig. 3 an example of the last-mentioned arrangement is seen. In this case the tray 8 is round and the perforator 14 is arranged in a raised platform 20 in the middle of the bottom. Besides, the construction functions in the same way as described above in the case of the first embodiment. The round tray 8 can be used for packing of e.g. forcemeat shape or ringformed cakes. Fig. 5 a,b,c shows a perforator with a downwards converging conical bottom 21 merging into the outer wall 15 and the inner wall 16, respectively, along roundwise bending lines 22 and 23.

In fig. 5a the perforator is in its starting position, that is in the state as it is being delivered from the producer of the tray. The point 13 has a small distance from the foil of the closure 3 and is standing perpendicular on this.

In fig. 5b the consumer deforms the perforator with a finger 24 which is pressing the conical bottom 21 upwards such that it is clapped elastically up about the bending lines 22 and 23 and now converges conically upwards. As it can be seen, the point 13 thereby is lifted so much that it penetrates the foil of the closure 3.

In fig. 5c the bottom 21 has leaped elastically back into its starting position. The consumer has inserted a finger 24 in the opening which the point 13 has formed in the foil of the closure 3 and is now tearing the foil up for totally removing it and optaining access to the contents of the packing. This operation is facilitated of the fact that the ledge 19 is situated below the rim 6 of the tray and thereby a little distance below the cover foil 3. Thereby is formed ample access for the finger 24 to get hold of the foil of the closure 3 as the finger, in addition to via the opening of the perforator, can get in below the foil of the closure 3 in the area between this and the ledge 19.

In the showed case the perforator had such a construction and was produced of such a plastic that the perforator was elastically deformed. In other cases the deformation will, however, wholly or partly be permanent by which the point 13 will remain standing in the position showed in fig. 5b. The perforated closure foil can, however, excellently still be teared up with a finger which immediately merely will press the point 13 somewhat back into the depression of the perforator.

In fig. 6 is from above seen a perforator which is placed in an incision 18 in a corner of a rectangular tray 2. The perforator has form of a circular solid of revolution and the point 13 has a direction perpendicular on the foil of the closure and is situated a little distance below this.

Fig. 7 a,b,c show the same perforator in section. As it can be seen, the outer wall 15 of the perforator is in this case provided with a number of symmetrically placed waves 25. The outer wall 15 therefore assumes character of a bellow.

In fig. 7a the perforator is seen in its starting position.

In fig. 7b the consumer with a finger is deforming the perforator with an upwards directed pressure. The perforator yields readily as the outer wall 15, functioning as a bellow, is pressed together in the waves 25. Therefore only a small pressure is necessary for deforming the perforator, and that means that even persons having weak fingers can easily operate the perforator and use it for opening the packing.

In fig. 7c the perforator elastically has leaped a little back and has thereby pulled the point a little down into the opening of the perforator. The main of the deformation imparted to the perforator is, however, permanent. The bellow-formed outer wall 15 has namely settled in the waves. As in the previous example the consumer has inserted a finger 24 in the opening formed by the point 13 in the foil of the closure 3 and is now tearing it up. Fig. 8 and 9 shows a variant of the embodiment showed in fig. 6 and 7 with bellow-formed outer wall. The perforator is seen from above in fig. 8. The opening of the perforator has a section 26 being sufficiently large for inserting a finger. This wide section 26 merges in the corner of the tray into another section 27 which is so narrow that it, conversely, not is possible to insert a finger

Fig. 9a shows the perforator in its starting position. The outer wall 15 is also in this case provided with waves 25 causing the outer wall to function as a bellow, but now the waves are asymmetrically placed, that is with the largest wave-formation on the right hand or towards the middle of the tray, and the smallest wave-formation on the left hand or towards the corner of the tray. The point is standing perpendicular on the cover foil 3 a small distance below this.

In fig. 9b the consumer is with a finger 24 acting on the perforator from below with an upwards directed pressure. The bellow-formed outer wall 25 has yielded for the pressure and has brought the point 13 up into contact with the foil of the closure 3. The perforating of this is just going to start.

In fig. 9c the point 13 has broken through the foil of the closure 3. As the wave-formation is asymmetrical the perforator also will deform asymmetrical and for the most part on the right hand. This implies that the point not merely is pricking a hole in the foil of the closure 3 but now directly is shearing a long tear in this as the point during the asymmetrically deformation of the perforator is forced into a movement going from the position showed in fig. 9 to the position showed in fig. 9d.

In fig. 9e the consumer has, as in the previous examples, inserted a finger 24 in the opening which the point 13 has formed in. the foil of the closure 3 and is now tearing the foil up for removing it totally. The point 13 is, however, in this case brought completely out of the wide section 26 of the opening, serving to insert the consumers finger 24, and into the narrow section 27 of the opening. The consumer can therefore easily with a finger get in below the cover foil without in any way to be bothered of the point 13, as this now is in the narrow section 27 where the finger is not able to get in. The consumer such will not by accident unintentionally could stick himself on the point.

The perforator showed in fig. 6 and 7 with asymmetrical waves in the outer wall 15 has in addition the very large advantage that the point by operating the perforator is shearing a long tear in the foil of the closure. Thereby the consumer easily can come in below and get hold of the already teard foil.

Fig. 10 and 11 shows an embodiment for a perforator with asymmetrically placed waves 28 in the inner wall 16. The opening, as in fig. 10 is seen from above, is oval and tapers in the direction towards the corner of the tray 2. The waves 28 exist, as shown in fig. 11 a,b,c, only on the left hand of the inner wall 16 or in the side turned toward the corner of the tray.

in this case the perforator itself is asymmetrical having the point 13, in the starting position showed in fig. lla, placed close to the corner of the tray in the narrow area of the opening.

In fig. lla the point is situated immediately below the foil of the closure 3, thereby facilitating the penetrating process while the closure foil of the packing in return is more vulnerable for unintentionally being perforated by an accidentally outer influence. In many cases the point 13 therefore will be placed with a small safety distance (not shown) from the foil of the closure in the starting *p+5Xpositio which is also the state in which the filled and closed packing is distributed.

As shown in fig. lib, the consumer now can drive the point through the foil of the closure 3 by bending with a finger 24 the rim down into the corner where the perforator is arranged. Thereby the left side of the inner wall 16 is strechted as the waves 28 partly are straightened out. The remainer of the perforator is relatively rigid and is therefore holding the point 13 in position, while the foil of the closure 3 in the corner of the tray is forced down the point and is being perforated when bending the rim 6 down.

In fig. lie the consumer has, as in the previous examples, inserted the finger 24 into the opening which the point 13 has formed in the foil of the closure 3 and is now tearing the foil up for removing it totally and obtaining access to of the contents of the packing. The point 13 is standing out at the corner in the narrow area of the opening of the perforator where it is not to inconvenience of the consumer.

Fig. 12, 13 and l4a,b shows a point 29 which is stationary placed on the side wall 5 of the rectangular tray 2. The point 29 is formed as the intersection between a triangular formed indentation 30 in the side wall 5 and the upper termination 31 of this indentation 30.

In fig. 14a the consumer is pressing with a finger 24 the flexible closure foil 3 down the point 29, thereby breaking the foil.

The consumer can now, as shown in fig. 14b, insert the finger down through the formed opening in the foil of the closure and tear the foil up in the same way as in the other examples. Fig. 15 shows, in a larger scale, a section through a fragment of an inner wall 16 of a perforator with a point 13 which is placed on the top of a ledge 32 and is terminating the inner wall above at the top.

The point has a height h which is equal to or merely a little more than the thickness of the normal used closure foil, that is about 40-60 my. As the epidermis of a finger has a thickness which is larger than this thickness the point cannot penetrate the epidermis and wound the finger. The point has, however, a sufficient height for perforating the foil of the closure.

Fig. 16 shows an apparatus for forming a tray for the packing. The apparatur is generally designated by 33 and comprises a patrice 34 and a matrices 35.

The apparatur is used in a forming machine (not shown) , where the foil 37 is heated and hold between two planes 38 and 39. The heated foil is sucked down into the matrices 35 as is evacuated via channels 36 which is connected with a source of vacuum (not shown) . By finally pressing the patrice 34 down into the matrices 35 the tray is imparted its final form.

with this process, which is per se conventional, it is possible to form the foil with relatively sharp details. The process is, however, not able to form the point 13 of the perforator with such a large sharpness that it safely and easily can penetrate the closure foil of the packing. It has namely appeared, that the air below the point of the perforator is not escaping rapidly enough during the forming process. The foil in the point of the perforator is namely not cooled so rapidly that the air has enough time for escaping through the very narrow passage formed between the foil in the point of the perforator and the corresponding point of the tool before the foil is becoming so stiff that it not more is sufficiently formable. The point of the perforator will therefore in the reality be formed over a air cushion which is giving the point a round form instead of a sharp form.

For being able to form the point of the perforator with a sufficiently large sharpness the point 40 of the tool, corresponding to the point of the perforator, as by way of example can be a forming sprig 40 which, as shown in fig. 17 is let into the matrices 35, has grooves 41 which are led all the way out to the extreme end of the point of the sprig 40. The grooves communicate with the source of vacuum via one of the channels 36 for evacuating all of the air at the point below the foil before this is rendering so cold that it is not formable any more. The foil will therefore be deposited close about the forming point of the sprig by which the penetrating point 13 will assume the sharpness of this.

Instead of the grooves 41 the forming sprig 40 can be round or formed with faces or facets.

Fig. 18 shows, seen from above, the forming sprig showed in fig. 17 but in another embodiment where the sprig instead of the grooves 41 has faces or facets 42. These faces or facets can be better seen in fig. 19 as, in a larger scale, shows a section through the extreme end of the forming sprig 40. As can be seen the sprig is triangular and it will therefore be hard for the foil during the forming process to be deposited close to the faces or facets 42 by which there between these and the foil arise wide passages for evacuatin of the air below the foil. The perforating point is therefore now not any more formed over a cushion but assumes instead the same sharpness as the sprig.

Fig. 20 shows a third embodiment for a forming sprig 43, placed in the matrices 35 of which there, in a larger scale, only can be seen a section. This forming sprig is moreover seen from above in fig. 21 and from below in fig. 22 and fragmentarily in a larger scale again from above in fig. 23 and in section from the side in fig. 24.

This embodiment is particularly advantageous as the forming sprig in this case is provided with an inner sprig 44 placed in a vertical through-going hole 45 in the forming sprig 43. Above at the top the inner sprig 44 merges into a point 46 as constitutes the part of the forming sprig 43 which is forming the proper point 13 of the perforator 14.

As it best can be seen in fig. 23 and 24 the inner sprig 44 is out of round and is therefore not filling the through-going hole 45 completely up in the transverse direction. As showed in fig. 23 the sprig such in one transverse direction has as lesser transverse measure than the diameter of the through-going hole by which there is leaved two through-going air slits between the inner sprig 44 and the forming sprig 43.

In the bottom of the forming sprig 43 there is formed a number of grooves 48 (also shown in fig. 22) which radiate from the through-going hole 45. A number of air channels 49 extend in addition vertically upwards from their respective grooves 48 to the top of the forming sprig 43.

This third embodiment for the forming sprig 43 is distinguished by its eminent ability to safely and effectively to being able to evacuate the air below the plastic foil of the perforating point 13 during the vacuum forming process. The air above the surface of the forming sprig is to a great extend evacuated via the air channels 49, the radial grooves 48 and the channels 36. Simultaneously, especially the air directly below the extreme part of the plastic foil of the of perforating point 13 is evacuated rapidly and effectively via the air slits 47 between the inner sprig 44 and the through-going hole 45. Thereby is secured that the perforating point is formed with the wanted sharpness.

The packing according to the invention can be produced to the same price as packings without a penetrating point.

In addition the perforator stands well protected against unintentional activating. Furthermore can the trays be formed with oblique sides allowing them to be stabled such that they take up as little of room as possible on the stock and during transportating.

The filled packing is closed by, with a large specific strength, to heat seal the foil of the closure on the tray. The packing is therefore safe and reliable.

The packing can easily and quickly be opened without using auxiliary tools but merely by, with a pressure of a finger, to driving the perforating point through the foil of the closure and tearing the foil up.

Claims

C A I M S

1. A packing for e.g. meat including a tray produced of a relatively rigid plastic foil and having a bottom- and side wall and a plane closure of a relatively flexible plastic foil for heat sealing on the tray, c h a r a r a t e r i z e d in that the foil of the tray is formed with a point situated at the closure plane for penetrating the foil of the closure.

2. A packing according to claim l, c h a r a r a t e r i z e d in that the penetrating point is surrounded of a ring-formed depression in the foil having an outer wall merging into the other tray, an inner wall merging into the penetrating point, and a bottom connecting the two walls

3. A packing according to claim l or 2, c h a r a r a t e r i z e d in that bottom of the depression bottom in section is in the main semicircular.

4. A packing according to claim l or 2, c h a r a r a t e r i z e d in that the bottom of the depression is in a conical surface converging against the bottom of the tray and relatively sharp is merging into the two walls of this.

5. A packing according to each of the claims l - 4, c h a r a r a t e r i z e d in that the outer wall of the depression is bellow-formed with a symmetrical wave-pattern.

6. A packing according to each of the claims l - 5, c h a r a r a t e r i z e d in that the outer wall of the depression is bellow-formed with an asymmetrical wave-pattern.

7. A packing according to each of the claims l - 6, c h a r a r a t e r i z e d in that the contour of the depression at the transition to the remaining tray is delimiting an opening having a wide section allowing a finger to be inserted and a narrow section not allowing this.

8. A packing according to each of the claims 1 - 7, c h a r a r a t e r i z e d in that the penetrating point stepwise is merging into the inner wall of the depression and having a height as corresponds to the thickness of the foil of the closure or merely is somewhat larger than this thickness.

9. A packing according to claim 1, c h a r a r a t e r i z e d in that there in the side wall of the tray is formed an inwardly turning depression as at the closure plan is forming the penetrating point.

10. A method for producing a packing for e.g. meat, by which the packing consists of a relatively rigid plastic foil and having a bottom- and side wall and a plane closure of a relatively flexible plastic foil for heat sealing on the tray, and the foil of the tray is formed with a point situated at the closure plane for penetrating the foil of the closure, c h a r a r a t e r i z e in that the tray is vacuum-formed in a matrices with a sprig formed, in the main, as the inner side of the penetrating point.

11. A tool for producing a packing for e.g. meat, by which the packing consists of a relatively rigid plastic foil and having a bottom- and side wall and a plane closure of a relatively flexible plastic foil for heat sealing on the tray, the foil of the tray is formed with a point situated at the closure plane for penetrating the foil of the closure, and the tray is vacuum-formed in a matrices with a sprig formed, in the main, as the inner side of the penetrating point, c h a r a r a t e r i z e d in that this sprig consists of an outer sprig and of an inner sprig placed in a central through-going hole in the outer sprig, and the through-going hole and the inner sprig are formed in a such a way in the transverse direction that there between the inner sprig and the through-going hole is left at least one air slit extending downwards from the over side of the outer sprig to the under side of this and communicating with the source of vacuum.

AMENDED CLAIMS

[ received by the International Bureau on 04 January 1996 (04.01.96); original claims 1-11; replaced by amended claims 1-11 (3 pages)]

1. A packing for e.g. meat including a tray produced of a relatively rigid plastic foil and having a bottom- and side wall and a plane closure for heat sealing on the tray, wherein said plane closure is defining a closure plane and is produced of a relatively flexible plastic foil, c h a r a c t e r i z e d in that a point for penetrating the foil of the closure is formed of said relatively rigid plastic foil integral with the tray, and that said point is situated inside the tray pointing towards the closure plane.

2. A packing according to claim l, c h a r a c t e r i z e d in that the penetrating point is surrounded of a ring- formed depression in the foil having an outer wall merging into the other tray, an inner wall merging into the penetrating point, and a bottom connecting the two walls

3. A packing according to claim i or 2, c h a r a c t e r i z e d in that the bottom of the depression in section is in the main semicircular.

4. A packing according to claim l or 2, c h a r a c t e r i z e d in that the bottom of the depression is in a conical surface converging against the bottom of the tray and is relative sharply merging into the two walls of this.

5. A packing according to each of the claims 1 - 4, c h a r a c t e r i z e d in that the outer wall of the depression is bellow-formed with a symmetrical wave-pattern.

6. A packing according to each of the claims l - 5, c h a r a c t e r i z e d in that the outer wall of the depression is bellow-formed with an asymmetrical wave-pattern. 7. A packing according to each of the claims 1 - 6, c h a r a c t e r i z e d in that the contour of the depression at the

5 transition to the remaining tray is delimiting an opening having a wide section allowing a finger to be inserted and a narrow section not allowing this.

8. A packing according to each of the claims l - 7, c h a r a lO c t e r i z e d in that the penetrating point stepwise is merging into the inner wall of the depression and having a height as corresponds to the thickness of the foil of the closure or merely is somewhat larger than this thickness.

15 9. A packing according to claim 1, c h a r a c t e r i z e d in that there in the side wall of the tray is formed an inwardly turning depression as at the closure plan is forming the penetrating point.

20 10. A method for producing a packing for e.g. meat including a tray produced of a relatively rigid plastic foil and having a bottom- and side wall and a plane closure for heat sealing on the tray, wherein said plane closure is defining a closure plane and is produced of a relatively flexible plastic foil, a

25 point for penetrating the foil of the closure is formed of said relatively rigid plastic foil integral with the tray, and said point is situated inside the tray pointing towards the closure plane, c h a r a c t e r i z e d in that the tray is vacuum-formed in a matrices with a sprig formed, in the main,

30 as the inner side of the penetrating point.

11. A tool for producing a packing for e.g. meat including a tray produced of a relatively rigid plastic foil and having a bottom- and side wall and a plane closure for heat sealing on 35 the tray, wherein said plane closure is defining a closure plane and is produced of a relatively flexible plastic foil integral with the tray, a point for penetrating the foil of the closure is formed of said relatively rigid plastic foil integral with the tray, said point is situated inside the tray pointing towards the closure plane, and the tray is vacuum-formed in a matrices with a sprig formed, in the main, as the inner side of the penetrating point, c h a r a c t e r i z e d in that this sprig consists of an outer sprig and of an inner sprig placed in a central through-going hole in the outer sprig, and the through-going hole and the inner sprig are formed in a such a way in the transverse direction that there between the inner sprig and the through-going hole is left at least one air slit extending downwards from the over side of the outer sprig to the under side of this and communicating with the source of vacuum.

AMENDED SHEET (ARTICLE 19)