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WO1996001179A1 - Emballage - Google Patents

Emballage Download PDF

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Publication number
WO1996001179A1
WO1996001179A1 PCT/AU1995/000404 AU9500404W WO9601179A1 WO 1996001179 A1 WO1996001179 A1 WO 1996001179A1 AU 9500404 W AU9500404 W AU 9500404W WO 9601179 A1 WO9601179 A1 WO 9601179A1
Authority
WO
WIPO (PCT)
Prior art keywords
tray
peripheral edge
edge region
deforming
die
Prior art date
Application number
PCT/AU1995/000404
Other languages
English (en)
Inventor
Wayne Phillip Portelli
Louis Magyar
Original Assignee
Drypac Pty. Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from AUPM6655A external-priority patent/AUPM665594A0/en
Priority claimed from AUPM7905A external-priority patent/AUPM790594A0/en
Application filed by Drypac Pty. Ltd. filed Critical Drypac Pty. Ltd.
Priority to AU28747/95A priority Critical patent/AU701551C/en
Priority to EP95924104A priority patent/EP0768945A4/fr
Publication of WO1996001179A1 publication Critical patent/WO1996001179A1/fr

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C53/00—Shaping by bending, folding, twisting, straightening or flattening; Apparatus therefor
    • B29C53/02—Bending or folding
    • B29C53/025—Bending or folding using a folding bag
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C57/00—Shaping of tube ends, e.g. flanging, belling or closing; Apparatus therefor, e.g. collapsible mandrels
    • B29C57/12—Rim rolling
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D77/00—Packages formed by enclosing articles or materials in preformed containers, e.g. boxes, cartons, sacks or bags
    • B65D77/003—Articles enclosed in rigid or semi-rigid containers, the whole being wrapped
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65D—CONTAINERS FOR STORAGE OR TRANSPORT OF ARTICLES OR MATERIALS, e.g. BAGS, BARRELS, BOTTLES, BOXES, CANS, CARTONS, CRATES, DRUMS, JARS, TANKS, HOPPERS, FORWARDING CONTAINERS; ACCESSORIES, CLOSURES, OR FITTINGS THEREFOR; PACKAGING ELEMENTS; PACKAGES
    • B65D81/00—Containers, packaging elements, or packages, for contents presenting particular transport or storage problems, or adapted to be used for non-packaging purposes after removal of contents
    • B65D81/24—Adaptations for preventing deterioration or decay of contents; Applications to the container or packaging material of food preservatives, fungicides, pesticides or animal repellants
    • B65D81/26—Adaptations for preventing deterioration or decay of contents; Applications to the container or packaging material of food preservatives, fungicides, pesticides or animal repellants with provision for draining away, or absorbing, or removing by ventilation, fluids, e.g. exuded by contents; Applications of corrosion inhibitors or desiccators
    • B65D81/264—Adaptations for preventing deterioration or decay of contents; Applications to the container or packaging material of food preservatives, fungicides, pesticides or animal repellants with provision for draining away, or absorbing, or removing by ventilation, fluids, e.g. exuded by contents; Applications of corrosion inhibitors or desiccators for absorbing liquids
    • B65D81/265—Adaptations for preventing deterioration or decay of contents; Applications to the container or packaging material of food preservatives, fungicides, pesticides or animal repellants with provision for draining away, or absorbing, or removing by ventilation, fluids, e.g. exuded by contents; Applications of corrosion inhibitors or desiccators for absorbing liquids the absorbent being placed beneath a false bottom

Definitions

  • This invention relates broadly to packaging. More specifically this invention relates to trays for packaging which are wrapped in plastic film or plastic wrap, methods of producing such trays, and apparatus for producing such trays.
  • plastic trays used for the packaging of foodstuffs such as red meat, fish, poultry, garden produce and the like although it is to be understood that the invention is capable of broader application.
  • foodstuffs such as red meat, fish, poultry, garden produce and the like although it is to be understood that the invention is capable of broader application.
  • food to be packaged would be placed on such a tray and then wrapped in polythene wrap or film to seal it off from the atmosphere and preserve its freshness until sale.
  • the term "tray” shall not be limited to flat or shallow containers. Further the term shall not be limited to containers having four straight edged sides.
  • the trays defined in this specification might contain chickens and that the tray might be configured to conform with the outline of the shape of the chicken.
  • plastic shall be construed to include any group of materials, synthetic or natural, which may be shaped when soft and then hardened, including resins, resinoids, polymers, cellulose derivatives, casein materials and proteins.
  • foam trays for example of expanded polystyrene foam
  • foam trays have been widely used for the packaging of foodstuffs.
  • foam is a relatively soft material and the edges of the tray are rounded, the terminal edges thereof do not have a tendency to cut plastic film within which the trays are wrapped.
  • Foam cannot be recycled and if it is burnt, environmentally damaging gaseous compounds can be released into the atmosphere. Consequently there is a trend away from the use of foam trays to the use of plastic trays which can be recycled.
  • plastic trays used in packaging are formed by a thermoforming operation.
  • a method of producing a plastic tray having a peripheral edge region terminating in a terminal edge which is deformed such that the terminal edge is displaced out of a wrap path around the tray including: providing a plastic tray having a peripheral edge region terminating in a terminal edge; heating the peripheral edge region of the tray such that said peripheral edge region becomes malleable and the remainder of the tray remains non- malleable; and deforming the peripheral edge region of the tray by bringing an appropriately configured deforming means into engagement with said peripheral edge region of the tray to displace the terminal edge out of the wrap path, the deforming being effected by relative movement between the tray and the deforming means.
  • the method includes cooling the peripheral edge region of the tray such that it sets and hardens with the terminal edge displaced out of the wrap path.
  • the step of heating the peripheral edge region of the tray includes producing a sharp transition from malleable to non-malleable plastic which forms a fold line about which said peripheral edge region is deformed.
  • said deforming means is a die and said heating the peripheral edge region of the tray includes heating the die which in turn heats the peripheral edge region of the tray when brought into heat conductive contact therewith.
  • deforming the peripheral edge region includes rolling the peripheral edge region.
  • the edge region around the full periphery of the tray is rolled substantially simultaneously.
  • the die is configured such that upon engagement with the tray, it heats the peripheral edge region of the tray, and when the peripheral edge region is malleable, it rolls the peripheral edge region of the tray.
  • heating the peripheral edge region of the tray includes creating a temperature gradient across the peripheral edge region, the temperature being hotter adjacent the terminal edge and decreasing inwardly therefrom.
  • the temperature gradient across the peripheral edge region is obtained by configuring the die such that it is in heat conductive contact with part of the peripheral edge region of the tray longer than other parts thereof.
  • rolling the peripheral edge region of the tray includes moving the tray into engagement with the die.
  • the heating comprises blowing hot air over the peripheral edge region of the tray.
  • the portion of the tray laterally inwardly of the peripheral edge region is shielded from the hot air blast.
  • the deforming means includes a former and a complementary engagement formation, the former being moved into engagement with the complementary engagement formation to deform the peripheral edge region.
  • the cooling includes actively cooling the peripheral edge region of the tray using cooling water.
  • This invention also extends to a plastic tray produced by the methods described above.
  • a method of joining two tray members to each other to form a unitary two-piece tray including: providing base and cover members each having a peripheral edge region terminating in a terminal edge; mounting the cover member in a superimposed relationship on the base member such that the peripheral edge regions of the two trays are substantially in alignment with each other; heating the peripheral edge regions of the base and cover members such that said peripheral edge regions become malleable and the remainder of the base and cover members remain non-malleable; and deforming the peripheral edge regions of the base and cover members laterally inwardly, by bringing an appropriately configured deforming means into engagement with said peripheral edge regions, so as to crimp the two peripheral edge regions to each other to form a unitary two-piece tray.
  • the terminal edges of respectively the cover and base members are also displaced out of the wrap path.
  • This invention also extends to a two-piece plastic tray including: a base member, and a cover member mounted in superimposed relationship on the base member, each said member including a peripheral edge region terminating in a terminal edge, wherein the peripheral edge regions of the base and cover members are crimped together so as to form a unitary two-piece tray.
  • the peripheral edge regions of the base and cover members are deformed downwardly and laterally inwardly by said crimping such that the terminal edges thereof are displaced laterally inwardly out of the wrap path.
  • the peripheral edge region which is deformed laterally inwardly has a width of at least 2 mm.
  • the cover member is water permeable and the base member is water impermeable. This may be accomplished by having a plurality of apertures defined in the cover member.
  • Moisture absorbent means may be sandwiched between the base and cover members for absorbing moisture on the tray.
  • the moisture absorbent means comprises a particuiate moisture absorbing material contained within a water permeable bag.
  • said base member typically defines a first plurality of spaced reinforcing rib formations and the cover member typically defines a second plurality of spaced reinforcing rib formations extending transversely to said first plurality of rib formations.
  • This invention also extends to a plastic tray including a peripheral edge region terminating in a terminal edge, wherein the peripheral edge region is deformed laterally inwardly such that the terminal edge is displaced out of a wrap path around the tray.
  • apparatus for producing a plastic tray including a peripheral edge region terminating in a terminal edge, wherein the peripheral edge region is deformed laterally inwardly such that the terminal edge is displaced out of a wrap path around the tray including: heating means for heating the peripheral edge region of the tray to a temperature at which it is malleable; and an appropriately configured deforming means for deforming the peripheral edge region of the tray and displacing the terminal edge of the tray out of the wrap path, the deforming means being moved relative to the tray to engage said tray and effect said deforming.
  • the deforming means includes a die for deforming by rolling the peripheral edge region of the tray.
  • the heating means acts to heat the die which heats the peripheral edge region of the tray by being brought into heat conductive engagement therewith.
  • the die is configured so as to engage the edge region of the tray around the full periphery thereof and to roll said peripheral edge region substantially simultaneously in a single step.
  • the die is configured so as to heat the peripheral edge region of the tray when it initially engages the tray to a temperature at which the edge region is malleable, and thereafter to roll the peripheral edge region of the tray.
  • this embodiment also includes an ejector for detaching the tray from the heated die once the deforming has been carried out.
  • the heating means includes a hot air blast which is directed onto the peripheral edge region of the tray.
  • the deforming means includes a former and a complementary deforming formation, the former being movable relative to the complementary deforming formation.
  • the former is typically a rigid body comprising a plurality of linear or straight edge portions and a plurality of corner portions.
  • the former comprises an inflatable tube or hydraulic cylinder.
  • the apparatus includes shield means for shield that portion of the tray laterally inwardly of the peripheral edge region, from the hot air blast.
  • the apparatus of this embodiment also includes cooling means for actively cooling the peripheral edge region of the tray.
  • Such cooling means typically includes cooling water which is passed over the former.
  • Fig 1 is a schematic sectional front elevation of an apparatus for performing the invention in accordance with a first embodiment of the invention, prior to the deforming operation taking place;
  • Fig 2 is a schematic sectional front elevation of the apparatus of Fig 1 after the deforming operation has taken place;
  • Fig 3 is a schematic sectional front elevation of an apparatus for performing the invention in accordance with a second embodiment of the invention, prior to the deforming operation taking place;
  • Fig 4 is a schematic sectional front elevation of the apparatus of Fig 3 after the deforming operation has taken place;
  • Fig 5 is a schematic sectional front elevation of an apparatus for performing the invention in accordance with a third embodiment of the invention, prior to the deforming operation taking place;
  • Fig 6 is a schematic sectional front elevation of the apparatus of Fig 5 after the deforming operation has taken place;
  • Fig 7 is a schematic sectional front elevation of an apparatus for performing the invention in accordance with a fourth embodiment of the invention, prior to the deforming operation taking place;
  • Fig 8 is a schematic sectional front elevation of the apparatus of Fig 7, after the deforming operation has taken place;
  • Fig 9 is a perspective view of apparatus in accordance with the first embodiment
  • Fig 10 is a perspective view of the leading edge of the apparatus of Fig 9 showing the manner in which the straight or linear edge and corner former portions are brought into sequential engagement with the tray edge;
  • Fig 11 is an exploded perspective view of the apparatus of Figs 9 and 10;
  • Fig 12 is a schematic sectional view of an edge of a thermoformed tray which is particularly suitable for use in implementing this invention
  • Fig 13 is a schematic sectional view of the edge of the tray of Fig. 12 after it has been deformed out of the wrap path in accordance with the invention.
  • Fig. 14 is a top perspective view of a two-piece tray in accordance wjth an embodiment of this invention.
  • Fig. 15 is a bottom perspective view of the tray of Fig. 14;
  • Fig. 16 is a cross-sectional view of the tray of Figs. 14 and 15, the section through XVI-XVI.
  • reference numeral 1 refers generally to apparatus according to the invention for carrying out the method of the invention.
  • the apparatus 1 comprises broadly heating means in the form of a hot air duct 2 through which hot air is blasted, deforming means in the form of a former
  • the anvil 4 is a deforming formation which is complementary in shape to said former 3. Cooling means (not shown) in the form of water cooling are also provided.
  • a plastic tray 5 to be deformed by the apparatus 1 is mounted on a substantially planar support surface 7.
  • the tray 5 has a base 8, a sloping side wall 9 extending up from the base 8, a peripheral rim 10 extending around the top of the side wall 9, a peripheral edge region indicated by the numeral 11 and a sharp razor-like terminal edge 12.
  • the peripheral edge region 11 is heated and deformed in carrying out the method of this invention. This is discussed in more detail below.
  • the former 3 is a solid block slidable along the support surface 7 towards and away from the anvil 4.
  • the former 3 may be driven by any suitable mechanical drive means.
  • Such drive means are well known to persons skilled in the art and as such will not be described in any further detail here.
  • the hot air duct 2 is positioned above the peripheral edge region 11 of the tray 5 and directs hot air blown through the duct 2 onto the edge region 11.
  • the hot air may be provided by any suitable hot air supply means. Such air supply systems are well known to persons skilled in the art and as such will not be described in any further detail here.
  • the anvil 4 is formed by a clamping foot 13 pivotally mounted on a clacker box 14. This pivotal mounting enables the anvil to be removed from underneath the peripheral edge region 11 when the peripheral edge region 11 has been deformed.
  • thermoformed plastic tray 5 typically having a sharp terminal edge 12
  • the clamping foot 13 placed over the underside of the rim 10 of the tray 5.
  • Hot air is then blown through the hot air duct 2 heating up the peripheral edge region 11 of the tray 5.
  • Fig 1 The configuration of components at this stage of the operation is shown in Fig 1.
  • the former 3 When the plastic material of the tray reaches the temperature at which it becomes malleable, 150 to 250°C, the former 3 is brought into operative engagement with the peripheral edge region 11 deforming it. In the fully deformed position the operative surface of the former 3 is adjacent the complementary operative surface of the anvil 4.
  • the structural features of the former are described in more detail below.
  • the hot air blast is then interrupted and the peripheral edge region 11 of the tray 5 is cooled so that it sets in the deformed configuration.
  • the configuration of components at this stage of the operation is shown in Fig 2.
  • the former 3 is then moved outwardly away from the peripheral edge region 11 and the clamping foot 9 is pivoted inwardly and upwardly relative to the clacker box 14 to free it from the deformed peripheral edge region 11.
  • the tray 5 is then removed from the support surface 7 and the cycle is repeated with another tray 5.
  • the cycle time for the entire operation would be of the order of three to five seconds. Of this the cooling time would be a half to three quarters of a second.
  • the cycle time is obviously dependent upon the aggressiveness of the heating of the edge region 11 of the tray 5, the rate at which the edge region 11 is cooled, and the gauge of the tray 5 being subjected to the post-forming treatment. Obviously the greater the rate of heat transfer for both heating and cooling operations, the shorter will be the cycle time. A short cycle time is obviously desirable as this will enable more containers to be treated per unit time.
  • Figs 9 to 11 illustrate the apparatus of the first embodiment in some detail using the same reference numerals as in Figs 1 and 2.
  • the apparatus 1 has a rectangular box-like appearance. There are four hot air ducts 2 directing air along the four edges 12 of the rectangular tray 5. Each of the ducts 2 fans outwardly from a round pipe cross-section at its upper end to an elongate slot cross-section at its lower end which extends along the length of the tray edge 12.
  • cooling water is used to cool and harden the deformed peripheral edge region 11.
  • the cooling water is circulated through pipes 30 mounted on the former 3 thereby acting to cool the former 3 which in turns cools the region 11.
  • the former 3 which extends circumferentially around the tray edge 12 is divided up into a plurality of portions.
  • linear portions 34, 35, 36, 37 extend along the straight edges of the tray 5 and four corner portions 38, 39, 40, and 41 are positioned at the corners of the tray 5.
  • the linear portions 34-37 of the former 3 are sized to overlap the corner radius of the tray 5.
  • This overlap is very useful in rounding off the tray edge in the corner region satisfactorily as otherwise it has a tendency to form sharp points.
  • the linear portions 34-37 overlap the corner radius of the tray 5 causing the peripheral edge region 11 in the corner radius to taper upwardly in the configuration shown by numerals 42 in Fig 10.
  • the straight edge or linear portions 34-37 are then retracted back from the tray edge and the corner portions 38-41 actuated and brought into engagement therewith.
  • the linear and corner portions cannot be actuated to engage the tray edge simultaneously as there is overlap between the two.
  • the corner portion engages the tray edge, it engages the tapered corner and deforms it into a neat tray edge corner having a smooth blended form with a rounded profile.
  • Another particularly desirable feature is the maintaining of the support surface 7 at ambient temperature or even colder to maintain some rigidity in the rim 10 of the tray 5 when hot air is blown through the duct 2. This is important to get the region 11 to bend at the correct point, that is without bending the rim 10.
  • the contact of the rim 10 with the cold surface 7 counteracts the heating by the hot air.
  • the upper side of the rim 10 is shielded by the ciackerbox 14 and clamping foot 13 which is interposed between the hot air blast and the rim 10. It is desirable that some rigidity be maintained in the laterally outer portion of the rim 10 as this is the point around which the peripheral edge region 11 is folded. Further the rigidity of the rim 10 also acts as a brake to the former portions 34- 41 defining the end of the stroke thereof. If the rim 10 is too hot and malleable it will simply be deformed by the advancing former portions 34-41.
  • Fig 11 in addition to the features shown in the earlier drawings, shows conduits 45 conduiting compressed air to the clacker box 14 for moving the feet 13 of the ciackerbox 14 inwardly and out from under the rim 10 of the tray 5.
  • the embodiment illustrated in Figs 3 and 4 is very similar to that shown in Figs 1 and 2.
  • the same reference numerals have been used to refer to the same components as in Fig 1.
  • the only difference between these two embodiments lies in the configuration and action of the former 3.
  • the edge region 11 As it is brought into engagement with the peripheral edge region 11 of the tray 5, which in this embodiment is horizontally extending, the edge region 11 is curled or rolled upwardly and around so as to form the curved or rounded edge for the tray.
  • the end result is substantially the same as with the first embodiment.
  • the third embodiment illustrated in Figs 5 and 6 is also very similar to that shown in Figs 1 and 2. Unless otherwise specified, the same reference numerals have been used to refer to the same components as in Figs 1 and 2. The only difference between these two embodiments lies in the substitution of the inflatable tube 20 for the former 3. The tube 20 is inflated with air and as it is inflated expands thereby deforming the edge region 11 of the tray as shown in Fig 6. Such tubes or bladders are well known to persons skilled in the art and as such they will not be described any further here. This embodiment is the most desirable from a maintenance point of view because it does not have any mechanically moving parts.
  • the fourth embodiment illustrated in Figs 7 and 8 is similar to the embodiment illustrated in Figs 1 and 2. Accordingly where appropriate, the same reference numerals have been referred to the same components as in Figs 1 and 2.
  • Fig 7 the tray 5 is positioned upside down on a support 24.
  • the support 24 is spaced beneath a deforming means which is a downwardly facing die 25 substantially in alignment therewith.
  • the die 25 is configured so as to heat and deform the peripheral edge region 11 of the tray 5 by rolling, when it is brought into contact therewith.
  • the die 25 may be heated by any suitable heating means. Such heating means will be well known to persons skilled in the art and are not discussed further in the specification.
  • One particularly suitable heating means for heating the die is electrical heating.
  • the support 24 is configured to complement the basic shape of the tray 5 to support the tray 5 when it makes contact with the die 25. It is particularly preferable that the support 24 supports the sidewall 9 of the tray 5 towards the rim end 10 thereof. This region is shown by numeral X in Fig. 7. The providing of the appropriate support is important to prevent inward deformation of the tray 5. If such support is not provided, the edge of the tray 5 may end up being uneven and/or distorted. The support 24 is moved towards the die 25 to the position shown in Fig. 8 to deform the peripheral edge region 11. Any suitable drive means may be used to achieve this. As the various drive means that are available will be well known to persons skilled in the art, they are not discussed further in the specification. One particularly suitable drive means is provided by a piston and cylinder assembly (not shown). An ejector 27 for detaching the trays 5 with deformed edges from the die
  • the ejector 27 is discussed in more detail below.
  • an inverted tray is provided or mounted on the support 24.
  • the terminal edge 12 forms the peripheral edge of the tray 5.
  • the support 24 is then moved upwardly towards the die 25 by actuating the piston and cylinder assembly.
  • the peripheral edge region 11 of the tray 5 is brought into contact with the die 25. This heats the peripheral edge region 11 of the tray making it malleable and then deforms or rolls the peripheral edge region 11 of the tray 5 such that the edge 12 is displaced out of the wrap path. This position is illustrated in Fig. 8.
  • the support 24 is then retracted downwardly away from the die 25.
  • the tray 5 would remain in contact with the die 25 after the support 24 was lowered or retracted. This is because the malleable plastic of the peripheral edge region 11 tends to adhere to the hot die 25.
  • the ejector 27 which is sandwiched between the base 8 of the tray 5 and the die 25 is then urged
  • SUBSTITUTE SHEET (RULE 261 downwardly away from the die 25 to detach the tray 5 from the die 25 causing it to drop onto the support 24.
  • Any suitable means can be used for urging the ejector 27 downwardly. As such mechanisms are well known in the art they are not discussed further in the specification. Separation of the tray 5 from the die 25 facilitates cooling of the peripheral edge region 11 of the tray 5 allowing it to harden in a deformed condition.
  • Fig. 12 illustrates the profile of the edge of a thermoformed tray which is somewhat different to that illustrated in the preceding drawings.
  • the tray in Fig. 12 has a rim 10, a peripheral edge region 11 and a terminal edge 12.
  • the profile of the rim 10 leading into the edge region 11 is more curved than the corresponding region of the tray in Fig. 1.
  • Fig. 13 this gives the finished tray product a more rounded peripheral edge region which is preferable to the edge region shown in Fig. 2.
  • the implementation of this invention may involve pre-heating the peripheral edge region 11 of the tray 5 before the tray 5 is fed into the apparatus of Figs. 7 and 8.
  • the pre-heating is effected by a heater comprising an electric heating element formed into the shape of the periphery of the tray 5 around the full perimeter thereof.
  • the heating element is arranged to be closely spaced, for example about 3mm, away from the edge 12 of the tray 5 during said pre-heating.
  • One particularly suitable plastic from which the trays can be made softens at between 100°C and 150°C and becomes molten near 200°C.
  • plastics can also be used in carrying out this invention and such other plastics may soften and become molten at temperatures different to those specified above.
  • Figs. 14 to 16 illustrate a two-piece tray indicated generally by reference 50 which can be treated, like a one-piece tray according to the method and by the apparatus described above.
  • the tray 50 comprises broadly a water impermeable base member 51 and a complementary water permeable cover member 52.
  • the members 51 and 52 are thermoformed from plastic and as such the individual members prior to attachment generally have a sharp terminal edge forming the outer periphery thereof such as that indicated by numeral 12 in Fig.1
  • the cover member 52 is superimposed over the base member 51.
  • the peripheral edge regions of the two members 51 and 52 are tightly crimped together by the deforming operation described above with reference to Figs. 1 , 2, 9, 10 and 11 to attach the two members to each other to form a unitary article.
  • the terminal edges 12 of the two members 51 and 52 are folded downwardly inwardly well out of the wrap path and the tray 50 presents a less aggressive edge 54 to the wrap path 55.
  • the crimping or deforming of the edges 12 of the two elements 51 and 52 out of the wrap path 55 performs the dual function of attaching the two members 51 and 52 to each other and providing a tray with a peripheral edge 54 which does not damage plastic wrap.
  • the tray 50 would generally be of rectangular configuration having a rectangular base 56 surrounded by a low peripheral sidewall 57. A circumferential peripheral rim 58 projects outwardly away from the upper end of the side wall 57.
  • the tray generally also includes the further features of a first plurality of longitudinally extending rib formations 59 on the base member 51 and a second plurality of rib formations 60 extending perpendicularly to said first plurality of rib formations 59 on the cover member 52. Further, apertures 61 are defined in the cover member 52 to facilitate the passage of moisture therethrough.
  • Water absorbent material 62 which is typically a granular material contained within a permeable bag, is sandwiched between the members 51 and 52 for absorbing exudate which issues from food carried on the tray 50 and drains through the apertures 61 in the cover member 52. The absorption of the moisture enables the tray and food packed thereon to retain a fresh aesthetically pleasing appearance for several days.
  • thermoformed plastic trays can be provided which are particularly suitable for wrapping in plastic film or wrap. This will lead to improved productivity in the wrapping of plastic trays. Further this invention enables the alteration to the trays to be carried out on a high volume assembly line scale at reasonable cost.
  • a yet further advantage of the method of this invention is that it facilitates the attachment of the two elements of a two-piece tray to each other to form a unitary tray assembly. It thus obviates the requirement of using adhesive to adhere the two-tray elements to each other.
  • a two-piece tray according to this invention is aesthetically pleasing, has a peripheral edge which does not damage plastic wrap within which it is wrapped, and has a good mechanical strength. All these factors render it extremely suitable for use in food packaging.
  • a further advantage of a tray having a deformed peripheral edge region is that the region is far less prone to cracking than trays having untreated peripheral edge regions.
  • Applicant believes that this is due to the heat treatment step in which the edge region is heated to a deformation temperature, and which has the effect of stress relieving the thermoformed plastic. This is analogous to the stress relieving of glass by a re-annealing process.
  • the heat treatment step may also effect some beading of the plastic by melting.
  • a yet further advantage of the bending over the edge of the tray is that it mechanically strengthens the rim of the tray. Trays for food packaging are exposed to various forces during the handling and transport thereof. Trays in accordance with preferred embodiments of this invention have rims of increased mechanical strength and thus are far less prone to this bending and deformation.
  • a further advantage of the deforming of the edge of the tray is that it substantially eliminates the presence of microscopic "hairs" on the tray. Hairs are minute strands of plastic which are generated when the trays are cut immediately after the thermoforming operation. Customers of the trays, especially in the food industry regard these hairs as a potential hazard to consumers and are increasingly seeking trays that are free of these microscopic hairs. It is to be understood that various alterations, modifications, and/or additions may be introduced into the constructions and arrangements of parts previously described without departing from the ambit of the invention disclosed herein.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Food Science & Technology (AREA)
  • Shaping Of Tube Ends By Bending Or Straightening (AREA)

Abstract

On décrit un procédé pour produire une barquette (5) en plastique dont la région périphérique (11) se termine par un bord (12) qui est recourbé vers l'intérieur de manière qu'il ne puisse pas couper le film venant envelopper la barquette (5). On chauffe la région périphérique (11) de la barquette (5) pour la rendre malléable, on la déformé en engageant une matrice de forme appropriée dans la région malléable (11), et on recourbe celle-ci vers l'arrière. On laisse alors la région (11) refroidir pour qu'elle se solidifie et durcisse sous sa forme recourbée. Dans une forme d'exécution préférée, on chauffe la barquette (5) en chauffant la matrice (25) qui est utilisée pour recourber la région périphérique (11). Cette invention s'étend également à un procédé pour fixer ensemble les deux éléments d'une barquette à deux éléments, et à un appareil permettant de mettre en oeuvre le procédé de l'invention.
PCT/AU1995/000404 1994-07-06 1995-07-06 Emballage WO1996001179A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AU28747/95A AU701551C (en) 1994-07-06 1995-07-06 Packaging
EP95924104A EP0768945A4 (fr) 1994-07-06 1995-07-06 Emballage

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
AUPM6655 1994-07-06
AUPM6655A AUPM665594A0 (en) 1994-07-06 1994-07-06 Packaging
AUPM7905A AUPM790594A0 (en) 1994-09-06 1994-09-06 Packaging
AUPM7905 1994-09-06

Publications (1)

Publication Number Publication Date
WO1996001179A1 true WO1996001179A1 (fr) 1996-01-18

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/AU1995/000404 WO1996001179A1 (fr) 1994-07-06 1995-07-06 Emballage

Country Status (2)

Country Link
EP (1) EP0768945A4 (fr)
WO (1) WO1996001179A1 (fr)

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US6061349A (en) * 1995-11-03 2000-05-09 Cisco Technology, Inc. System and method for implementing multiple IP addresses on multiple ports
US6104717A (en) * 1995-11-03 2000-08-15 Cisco Technology, Inc. System and method for providing backup machines for implementing multiple IP addresses on multiple ports
DE10122166A1 (de) * 2001-05-08 2002-11-14 Bosch Gmbh Robert Verfahren und Vorrichtung zur Herstellung von Kunststoffbehältern
US7146417B1 (en) 1995-11-03 2006-12-05 Cisco Technology, Inc. System for distributing load over multiple servers at an internet site
ITMI20120963A1 (it) * 2012-06-04 2013-12-05 Magic Pack S R L Vassoio per alimenti e procedimento per il suo ottenimento
ITMI20120962A1 (it) * 2012-06-04 2013-12-05 Magic Pack S R L Stampo per vassoio per alimenti e vassoio cosi' ottenuto
EP2727855A1 (fr) * 2012-06-04 2014-05-07 Magic Pack S.R.L. Plateau pour aliments et son procédé d'obtention
CN108349150A (zh) * 2015-08-31 2018-07-31 转化器生产有限责任公司 形成的具有平滑边缘的热塑性制品
JP2020511329A (ja) * 2017-02-28 2020-04-16 コンバーター マニュファクチャリング，エルエルシー 平滑縁及び任意選択で剥離可能な表面を有する形成された熱可塑性物品
US11376768B2 (en) 2019-01-16 2022-07-05 Tekni-Plex, Inc. Packaging tray and method of manufacture
USD1034193S1 (en) 2020-01-27 2024-07-09 Tekni-Plex, Inc. Packaging tray
US12258172B1 (en) 2024-02-20 2025-03-25 Michael R. Borse Tray for use with overwrapping

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* Cited by examiner, † Cited by third party
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US6061349A (en) * 1995-11-03 2000-05-09 Cisco Technology, Inc. System and method for implementing multiple IP addresses on multiple ports
US6104717A (en) * 1995-11-03 2000-08-15 Cisco Technology, Inc. System and method for providing backup machines for implementing multiple IP addresses on multiple ports
US6298063B1 (en) 1995-11-03 2001-10-02 Cisco Technology, Inc. System and method for providing backup machines for implementing multiple IP addresses on multiple ports
US7146417B1 (en) 1995-11-03 2006-12-05 Cisco Technology, Inc. System for distributing load over multiple servers at an internet site
DE10122166A1 (de) * 2001-05-08 2002-11-14 Bosch Gmbh Robert Verfahren und Vorrichtung zur Herstellung von Kunststoffbehältern
ITMI20120963A1 (it) * 2012-06-04 2013-12-05 Magic Pack S R L Vassoio per alimenti e procedimento per il suo ottenimento
ITMI20120962A1 (it) * 2012-06-04 2013-12-05 Magic Pack S R L Stampo per vassoio per alimenti e vassoio cosi' ottenuto
EP2727855A1 (fr) * 2012-06-04 2014-05-07 Magic Pack S.R.L. Plateau pour aliments et son procédé d'obtention
US10562222B2 (en) 2015-08-31 2020-02-18 Converter Manufacturing, Llc Formed thermoplastic article having smooth edges
AU2019257532B2 (en) * 2015-08-31 2021-10-21 Converter Manufacturing, Llc Formed thermoplastic article having smooth edges
CN108349150A (zh) * 2015-08-31 2018-07-31 转化器生产有限责任公司 形成的具有平滑边缘的热塑性制品
US10562680B2 (en) 2015-08-31 2020-02-18 Converter Manufacturing, Llc Formed thermoplastic article having a smoothly-curved distal periphery
EP3344435A4 (fr) * 2015-08-31 2019-07-31 Converter Manufacturing, LLC Article thermoplastique modelé ayant des bords lisses
CN112045973A (zh) * 2015-08-31 2020-12-08 转化器生产有限责任公司 形成的具有平滑边缘的热塑性制品
EP3835028A1 (fr) * 2015-08-31 2021-06-16 Converter Manufacturing, LLC Article thermoplastique modelé ayant des bords lisses
JP2020511329A (ja) * 2017-02-28 2020-04-16 コンバーター マニュファクチャリング，エルエルシー 平滑縁及び任意選択で剥離可能な表面を有する形成された熱可塑性物品
JP7133560B2 (ja) 2017-02-28 2022-09-08 コンバーター マニュファクチャリング，エルエルシー 平滑縁及び任意選択で剥離可能な表面を有する形成された熱可塑性物品
JP2022177026A (ja) * 2017-02-28 2022-11-30 コンバーター マニュファクチャリング，エルエルシー 平滑縁及び任意選択で剥離可能な表面を有する形成された熱可塑性物品
US11376768B2 (en) 2019-01-16 2022-07-05 Tekni-Plex, Inc. Packaging tray and method of manufacture
US11697225B2 (en) 2019-01-16 2023-07-11 Tekni-Plex, Inc. Packaging tray and method of manufacture
USD1034193S1 (en) 2020-01-27 2024-07-09 Tekni-Plex, Inc. Packaging tray
US12258172B1 (en) 2024-02-20 2025-03-25 Michael R. Borse Tray for use with overwrapping

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Publication number Publication date
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EP0768945A4 (fr) 1998-07-29

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