Methods and apparatus for preserving pallet units of fresh perishables in modified atmosphere-containing bags

Abstract

Methods and apparatus for enclosing a palletized container of fresh containers of perishables inside a modified atmosphere-containing plastic bag stretched over the containers and over upwardly-extending margins of a plastic sheet placed between the pallet and the containers to seal the containers of perishables inside the bag and to facilitate forming a modified atmosphere inside the bag.

Description

BACKGROUND OF THE INVENTION

The fresh perishables trade uses modified atmosphere technologies on bagged and sealed pallet unit quantities of perishables to preserve freshness and reduce market losses during distribution. Current systems require that a pallet bag be placed over a unitized pallet of perishables, which are placed in containers. The pallet bag is then sealed to a plastic sheet positioned on top of the pallet under the unitized containers of perishables. Once the pallet bag is sealed, desired quantities of one or more gasses are injected into the pallet bag, creating a modified atmosphere, which benefits the enclosed perishables. U.S. Pat. Nos. Bolejack, et al. 5,014,495; 5,046,302; 5,111,639; and 5,314,286; Forgnone, et al. 6,532,717; and MacLeod, et al. 4,821,489 describe such methods and apparatus.

There is a need to improve the automation and consistency of the current systems. Current systems require up to three persons to operate effectively. These systems produce completed pallets at a rate of one per minute. The new methods and apparatus, with preferred embodiments, provide automated systems capable of reliably producing a finished pallet every 30 seconds, with fewer persons needed to operate the system.

SUMMARY OF THE INVENTION

A pallet bearing a plurality of containers of fresh perishables is placed on a conveyor. The perishables load is conveyed to a station where the unitized load is squeezed and lifted from the pallet, or is squeezed and the pallet lowered from the load, and a plastic sheet is automatically inserted on the pallet in the gap created above the pallet and below the suspended load. The margins of this bottom sheet extend beyond the edges of the pallet on all sides. See Bolejack, et al. U.S. Pat. Nos. 5,014,495; 5,111,639, and 5,314,286; and Forgnone, et al., U.S. patent application Ser. No. 10/785,868, filed in the United States Patent and Trademark Office Feb. 24, 2004, entitled “Apparatus And Methods For Enclosing Product Units,” for disclosures of such apparatus and methods. After the sheet is in place, and the containers of perishables are placed atop the pallet and sheet, the resulting pallet unit is conveyed to a bagging station. There, a plastic bag is automatically applied from above the palletized unit. The bag is stretched over, and then down the exterior surfaces of the stacked unit. Once the stretched film is released, the film, which forms a bag, is effectively pulled tightly against the exterior surfaces. Tension of the stretched bag against the pallet unit surfaces is also sufficient to brace/stabilize the palletized unit.

The new system may automatically position the overhanging margins of the bottom sheet upwards, against the sides of the perishables containers atop the pallet. The system then holds the sheet margins in a vertical position long enough for the descending bag to overlap and capture the sheet margins, and to hold the margins in the vertical, upward position against the perishables containers, inside the margins of the stretched bag. The bag opening is preferably positioned above the plane of the pallet surface, leaving a portion (e.g., two inches) of the vertically positioned bottom sheet exposed. The bag overlaps the remaining portions of the bottom sheet. Because the bag has been stretched, the elasticity of the bag pulls tight against, and holds the sheet margins in place. Once held by the stretched bag, the system holding the sheet margins upwards is withdrawn or cycled off. Alternatively, the sheet margins may overlie the margins at the opening of the bag.

Some perishables items require only one gas to create an appropriate modified atmosphere. For strawberries, this gas may be carbon dioxide. Typically, after bagging and sealing, any gases may be injected. Alternative, gases may be delivered over the perishables inside the bag as the bag is stretched over the perishables containers prior to sealing. A shrink hood stretching mechanism stretches the bag out and down adjacent to each corner of the unitized perishables. Gas delivery nozzles for creating a modified atmosphere environment inside the bag may be positioned under each corner of the bag stretching device. When activated, these nozzles deliver appropriate quantities of one or more gasses inside the bag to form a desired modified atmosphere as the bag is pulled and stretched over the unitized loads.

After leaving the bagging station, an in line tape or stretch wrap seal may be applied to the bag margins which overlap the vertically-positioned bottom sheet margins. The bag margins preferably lie substantially flat against the margins of the sheet and the container surfaces, providing a substantially smooth surface for tape or stretch film to be applied. Once properly applied, a seal is formed and substantially no gases may escape from the interior of the bag. These flat surfaces may also facilitate heat sealing of the bag to the sheet margins. See, e.g., U.S. Pat. Nos. Bolejack, et al. 5,014,495; 5,046,302; 5,111,639; and 5,314,286; Forgnone, et al. 6,532,717; and MacLeod, et al. 4,821,489 describing such methods and apparatus.

The permeability of the bag is preferably tailored to a specific perishable item. To form and maintain a desired modified atmosphere inside the sealed bag, the weight of the perishables must also be determined. By weighing each pallet, the respiration load of the perishable inside the enclosed bag can be determined. Based on this data, a system for punching or cutting calibrated holes in the pallet bag forms one or more appropriate openings in the bag, and/or an appropriate hole such that a breathing membrane or label may be placed over such a hole. The size of hole and type of label varies with the type and weight of the perishables item, and with the gas permeability of the bag. The breathing labels and/or calibrated holes help to maintain a desired modified atmosphere inside a bag, by balancing the desired components, e.g., carbon dioxide and oxygen, with the film permeability and perishable respiration load.

BRIEF DESCRIPTION OF THE DRAWINGS

The various features and advantages of this invention will become apparent in light of the following detailed description, taken together with the accompanying drawings, in which:

FIG. 1 shows a schematic plan view of a preferred embodiment of a layout of the bagging system of this invention;

FIG. 2 shows a perspective view of a system for applying a bag to a pallet of containers of perishables, and for forming a modified gas atmosphere inside the bag;

FIG. 3 shows a first embodiment of a system for positioning and holding the margins of a plastic pallet sheet vertically against the sides of palletized containers of perishables;

FIG. 4 shows a side elevation view of the plastic pallet sheet margins positioning/holding system device shown in FIG. 3;

FIG. 5 shows the operation of the device shown in FIGS. 3 & 4;

FIG. 6 shows a second embodiment of a device for holding the margins of a plastic pallet sheet vertically against the side of palletized containers of perishables;

FIG. 7 shows an embodiment of a system for delivering one or more modified atmosphere gases under a bag as the bag descends over a palletized perishables load;

FIG. 8 shows an embodiment of a station for taping the opening of a plastic bag to the margins of a plastic sheet that are positioned vertically against containers of perishables atop a pallet and plastic sheet;

FIG. 9 shows a side elevation view of a system for forming one or more holes in bags placed over a palletized load of containers of perishables for purposes of forming and maintaining a desired modified atmosphere inside such bags;

FIG. 10 shows the hole forming system of FIG. 9 in operation; and

FIG. 11 shows a hole formed by the device shown in FIGS. 9 and 10.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a schematic, plan view of palletized container of perishables bagging apparatus 10. In apparatus 10, conveyor 11 moves a plurality of pallets, each loaded with a plurality of containers of perishables, e.g., strawberry containers, stacked on the upper surface of the pallet. As an example, a pallet may carry 16 tiers, with six trays in each tier, and have an overall height of about 90 inches. Each tray may contain a plurality of strawberry baskets. The pallet itself may have a circumference in the range of 150 to 200 inches, and be rectangular or square in shape. Where the perishable is strawberries, the strawberries are preferably cooled to a temperature of about 33 degrees F., or about 4 degrees F. above the freezing point of the strawberries. The perishables are preferably cooled to, and maintained at an optimum storage temperature, before the bagging operation begins.

A plurality of pallets, each loaded with perishables, may be brought to in-feed 11, e.g., by forklift. In-feed 11 conveys the pallets, one at a time, to squeeze station 12. At squeeze station 12, hydraulically actuated, one or two pairs of opposed vertical walls are activated to engage and squeeze the pallet load of containers of perishables above the pallet with sufficient force to permit the floor plate beneath the pallet to be lowered from the load supporting position, or to raise the pallet load from the pallet. See, e.g., U.S. Pat. Nos. Bolejack, et al. 5,014,495; 5,046,302; 5,111,639; and 5,314,286; Forgnone, et al. 6,532,717; and MacLeod, et al. 4,821,489 describing such methods and apparatus. After the pallet and load have been separated from one another, a plastic sheet is automatically placed on the pallet in the gap formed between the unitized load and the pallet. The inserted sheet then rests on the pallet's upper surface. This sheet is generally flat, and the margins of the sheet extend beyond the edges of the pallet. After placement of the sheet on the pallet, the pallet may then be raised, or the pallet load may be lowered, to replace the perishables containers onto the plastic sheet atop the pallet. The pallet, with its plastic sheet and perishables atop the plastic sheet, is then conveyed on path 13 into bagging station 14.

At bagging station 14, a plastic bag of appropriate size, shape, type and gas permeability is automatically applied. The bag descends from a bag supply above the pallet of perishables, and is stretched to fit over the perishables and unitized containers of perishables. Simultaneously, the system automatically positions the overhanging margins of the deck sheet upwards to a vertical position against the sides of the perishables containers. The system holds these margins in this position for a time sufficient for the descending bag to overlap and capture these margins in the vertical upward position against the sides of the containers, and now inside the stretched pallet bag. The margins at the opening of the bag are positioned above the pallet, leaving a portion of the vertically-extended sheet margins exposed. Because the bag has been stretched, and released against the load, the elasticity of the bag pulls tight against, and holds the vertically positioned margins of the sheet in place. Thereafter, the system holding the sheet margins vertically upwards is withdrawn or cycled off Bagging apparatus of this type are, for example, the automatic Lachenmeier, Beumer, and Moeller stretch hood machine.

In preferred embodiments, as a bag descends over the perishables on the pallet, one or more gasses appropriate for creating a desired modified atmosphere inside the bag, and over the perishables, may be injected under the bag to blanket or cover the perishables as the bag is stretched over the perishables load. For this purpose, nozzles may be positioned under one or more corners of the bag so the bag descends over the perishables so that the gas is delivered at up to four locations, to form a desired modified atmosphere inside the bag.

The bagged palletized perishables leave bagging station 14 and passes on path 15 to sealing station 16. There, a taping mechanism applies tape or other suitable material where the bag overlaps the decking sheet, preferably around the entire circumference of the bagged palletized containers of perishables creating a substantially air-tight seal. The sealed palletized bagged perishables unit then passes on path 15 to weighing scale 18, for weighing. Using the weight of this unit, and the nature and temperature of the perishables, the respiration load for the perishable can be determined. From scale 18, the unit passes on path 17 to station 19 where, based in part on the measured weight, or respiration load, calibrated holes are formed in the bag as appropriate to maintain the desired modified atmosphere within the bag. Labels, membranes or other such devices may also, or alternatively, be applied to the bag to modify the permeability of the bag, and maintain a desired modified atmosphere within the bag for the respiration load as determined.

FIG. 2 shows pallet 22 bearing a load of perishables 20 with plastic sheet 21 between the pallet's upper surface and the bottom surface of the perishables. Sheet 21 extends over the margins of pallet 22 on all four sides.

FIGS. 3, 4 and 5 show scissors mechanism 23 which supports blades 24 and 27. As scissors mechanism 23 moves upward, blades 24 and 27 engage and move the margins of sheet 21 into the vertical position alongside the edges of the palletized load. These blades hold the margins in this vertical position until the bag has descended over the perishables, and over the margins of sheet 21. FIG. 4 shows blade 27 holding the sheet margins vertically against the side of the palletized load 20.

FIG. 6 shows the margins of plastic sheet 21 alternately held in vertical position by means of air from blowers 30 through 36. This air is delivered from compressor 37 through manifold 38.

FIG. 7 shows gas delivery system 40, which includes gas tanks 41 and 42, valve 43, manifold 44, hoses 45, 46, and 47, and nozzles 48, 49, and 50. In preferred embodiments, this gas delivery system delivers one or more gases inside the pallet bag as it descends over the palletized load to form a desired modified atmosphere inside the bag.

FIG. 8 shows unit 51, a bagged modified atmosphere-blanketed pallet of containers of perishables at taping station 16 where taping mechanism 52 applies tape to the periphery 53, where the bag overlaps vertically-extending deck sheet margins to seal them to one another. Alternatively, in FIG. 8, track 54A drives the tape mechanism around the pallet. The unitized load is stationery while the taping mechanism moves around the stationery load.

FIG. 9 shows system 60 for forming calibrated holes in the bag as an adjunct to maintaining the desired modified atmosphere inside the bag. In FIG. 9, this system is located at station 19. Hole-forming system 60 includes air compressor 61, controls 62 and manifold 63, one-way valve 64, and hole-forming cutter 66 with serrated blades formed on surface 67. Cutter 66 is housed within safety collar 68 and is actuated by depressing switch 69 on handle 70.

FIG. 10 shows an elevation view of hole-forming system 60 applied against bag surface 70 of unit 71. With collar 68 resting against bag surface 70, cutter 66 moves (right to left) to cut into and form holes of desired shape and pattern on bag surface 70. Cutter 66 is withdrawn and a special membrane may then be applied to cover the hole.

After the hole-punch and the calibrated membrane application processes, the completed, bagged, unitized pallet containing a desired modified atmosphere moves along on exit conveyor 19. A forklift can then remove the unitized pallet load for storage/distribution.

Claims

1. (canceled)

2. Apparatus comprising:

a squeezer for temporarily supporting containers of perishables above a pallet creating a gap such that a plastic sheet may be placed atop said pallet with margins of said sheet extending beyond the perimeter of said pallet;

a bag dispenser that stretches a plastic bag over said perishables and said containers and over the upwardly extending margins of the plastic sheet; then releases the stretching force so that said bag fits tightly over said perishables and said containers; and

a sealer for sealing said pallet and said perishables inside of said plastic bag.

3. (canceled)

4. (canceled)

5. (canceled)

6. (canceled)

7. (canceled)

8. The apparatus of claim 2, wherein said sealer comprises a heat sealer, a tape sealer, a wrapping system, or a gluing system.

9. The apparatus of claim 2, further comprising a gaseous pressure system or a mechanical system for positioning and holding the margins of said plastic sheet vertically upwardly from said pallet against the sides of said containers.

10. (canceled)

11-22. (canceled)

23. The apparatus of claim 2 further comprising a gas delivery system for delivering a gaseous modified atmosphere inside said bag.

24. The apparatus of claim 23 wherein said gas delivery system includes a plurality of injectors for delivering one or more gases inside said bag.

25. The apparatus of claim 24 wherein said gas delivery system includes one or more injectors linked to said bagging system.

26. The apparatus of claim 2 or claim 23 or claim 24 further comprising a hole-forming device for forming one or more holes in one or more sides of said bag to form and to maintain a desired, modified atmosphere inside said bag.

27. The apparatus of claim 2 or claim 23 or claim 24 further comprising a system for forming a desired modified atmosphere inside said bag based on the nature of the perishables, the weight of the perishables, and on the respiration load of the perishables inside said bag.

28. Apparatus comprising a system for sealing containers of perishables on a pallet that has a plastic sheet atop said pallet and beneath said containers, with margins of said sheet extending beyond the perimeter of said pallet; inside a plastic bag stretched tightly over said perishables, over said containers and over the upwardly extending margins of the plastic sheet that includes a sealer for sealing said pallet and said perishables inside of said plastic bag, and a system for forming a desired modified atmosphere inside said bag based on the nature of the perishables, the weight of the perishables, the permeability of the bag to oxygen and carbon dioxide, and on the respiration load of the perishables inside said bag.

29. The apparatus of claim 28 further comprising a hole-forming device for forming one or more holes in one or more sides of said bag to form and to maintain a desired, modified atmosphere inside said bag.

30. The apparatus of claim 9 wherein said system further comprises a system that secures said margins in a vertically upward position.