WO1989009729A1

WO1989009729A1 - Method and installation for packing of a carcass

Info

Publication number: WO1989009729A1
Application number: PCT/SE1989/000198
Authority: WO
Inventors: Lars Magnusson; Alve Stenfelt; Ingemar FRÖDERBERG
Original assignee: Frigoscandia Ab
Priority date: 1988-04-11
Filing date: 1989-04-11
Publication date: 1989-10-19
Also published as: SE8801309D0; SE8801309L

Abstract

In a method and an installation for packing a carcass (2) prior to freezing, storage and/or transport, a bag-like plastic cover (6) is pulled from below over the hanging carcass (2) and sealed after evacuation of the enclosed air. The installation comprises an overhead conveyor (1) with suspension means (3) for each carcass for conveying the carcasses to an evacuation equipment (9-11) for a pulled-on plastic cover (6) and to a heating equipment (12) for heating the plastic cover after evacuation to a temperature at which the plastic cover permanently assumes the shape imparted to it by the evacuation, and the cover surfaces in contact with one another are blocked.

Description

METHOD AND INSTALLATION FOR PACKING OF A CARCASS

The present invention relates to a method and an installation for packing a carcass prior to freezing, storage and/or transport.

At present, carcasses of e.g. cattle and hogs are frozen and stored whole or divided in, for example, sides or quarters which are subsequently divided into retail cuts. Some countries require packing of the carcasses after freezing, which is of course a hygienic improvement in relation to the handling of unprotected carcasses.

To make carcass handling even more hygienic, it has also been attempted to wrap the carcasses in some suitable plastic material before they are frozen. To make such ear- ly wrapping in, for- example, plastic material successful, the plastic material must be made to follow the irregular surface of the carcass without any intervening air layer to speak of. Moreover, the wrapping must retain during the entire handling period a shape closely conforming to the carcass.

Maintaining the wrapping essentially in contact with the entire surface of the carcass during freezing is high¬ ly important since the freezing time will be extended con¬ siderably if e.g. air pockets occur between the wrapping and the carcass surface. The contact of the wrapping with the carcass is also important during all subsequent car¬ cass handling because the risk that the wrapping will rup¬ ture during this handling is increased considerably unless the carcass surface imparts to the wrapping the requisite support and stability.

The wrapping prior to freezing as described above af¬ fords not only hygienic advantages; it is also advan¬ tageous in respect of quality and economy because it pre¬ vents drying-out of the carcass surface layer as well as weight loss. Furthermore, a gastight wrapping delays ran- cidification of the wrapped carcass and therefore gives a longer storage life. According to a prior art method for packing car¬ casses, a bag of an impervious material, such as plastic, is pulled from below over a hanging carcass and the end of an air evacuation hose, whereupon the bag is tightly sealed about the hose end, and the air is evacuated, caus¬ ing the bag to follow the carcass surface. Then the -bag is sealed above the carcass but below the end of the air eva¬ cuation hose.

Although this technique gives the desired advantages of early carcass packing, it suffers from the shortcoming that, if the bag should get a hole, it will resume more or less its original shape, which greatly- increases the risk that the bag is torn during the subsequent handling of the carcass which then will be exposed to air to practically the same extent as when there is no packing at all.

It is the object of the present invention to provide a packing which, besides affording the above-mentioned ad¬ vantages, also reduces the risk of tearing the bag in the event of a hole therein. This object is achieved by the method according to the invention in that the plastic cover after evacuation is heated sufficiently, but only so far that it can be made to permanently assume the shape obtained by the eva¬ cuation, and to achieve blocking of the cover surfaces in contact with one another, i.e. to cause these surfaces to strongly adhere to one another or be laminated permanently and without shrinking..

The installation according to the invention achieves the same object in that it comprises an overhead conveyor with suspension means for each carcass for conveying-the carcasses to an evacuation equipment for a pulled-on plas¬ tic cover and to a heating equipment for heating the plas¬ tic cover after the evacuation to, but not beyond, a tem¬ perature at which the plastic cover permanently assumes the shape imparted to it by the evacuation, and the cover surfaces in contact with one another are blocked, i.e. caused to strongly adhere to one another or be laminated permanently and without shrinking.

For carrying the invention into effect, the plastic of the plastic cover must be a thermoplastic with appro- priate blocking properties, i.e. the ability of two plas¬ tic surfaces to strongly adhere to one another or be lami¬ nated permanently and without shrinking upon a relatively moderate application of heat. It is essential that the temperature of heating is not higher than is necessary to achieve a blocking effect and the permanent shaping of the plastic cover into conformity with the carcass shape, be¬ cause otherwise the plastic cover may also adhere to the carcass surface, and then it will be exceedingly difficult to detach it from the carcass later on. Moreover, if the heating temperature were too high, the plastic could shrink, with the ensuing risk that it may rupture over a sharp edge on the carcass, or detach itself from the car¬ cass surface over a depression.

Preferred executions and embodiments of the invention are defined by the dependent claims.

The invention will be described in more detail below, reference being had to the accompanying drawings. Fig. 1 illustrates schematically an installation for the packing of carcasses in accordance with the method of the inven- tion. Fig. 2 illustrates schematically a preferred embodi¬ ment of the installation according to the invention. Figs. 3-6 are different cross-sectional views of an eva¬ cuating and heating cabinet utilised in the embodiment ac¬ cording to Fig. 2. The installation shown in Fig. 1 comprises an over¬ head conveyor 1 along which carcasses 2 are conveyed in succession hanging on hooks 3. Each carcass is hung on its hook 3 by means of a loop-shaped strap.

The installation is divided into at least two sta- tions along the conveyor. At each station, one or more of the sub-operations of the packing method are carried out. The carcasses 2 moving along the conveyor 1 first ar¬ rive at station A which has a supply of packing bags or covers in the form of a reel 5 from which a plastic cover 6 is pulled from below over the carcass 2, and the open upper end of the cover is fixed by means of a stretching unit 7. The stretching unit -7 comprises two slats 8 stretching out the upper end of the cover 6 so that the inner surfaces of the cover at the upper end are in es¬ sentially flat mutual engagement and are compressed be- tween the slats 8. The slats 8 are connected with two tubular members 9 positioned at the ends of the slats 8 and projecting into and engaging the cover to stretch out the upper end thereof. The tubular members 9 form passages into the interior of the cover 6, The tubular members are part of an air evacuation ■ equipment 10 which also has two air evacuating lines 11 each connectible to one of said tubular members 9 for eva¬ cuation of the air within the cover 6. The tubular members 9 may contain non-return valves preventing air from reentering the cover 6 when the evacuating lines 11 are disconnected from the tubular members 9.

After disconnection of the evacuating lines 11, the carcass 2 wrapped in the cover 6 is conveyed to a second station B along the conveyor 1. In the embodiment shown in Fig. 1, the second station B comprises a heating equipment in the form of a heating cabinet 12 into which the carcass wrapped in the cover 6 can be introduced and enclosed. Once the carcass 2 is inside the heating cabinet 12, the temperature thereof is increased for a relatively short time to about 100°C^ whereby the plastic of the cover 6 is caused to permanently assume the shape imparted to it by the evacuation, and furthermore the surfaces of the cover 6 in contact with one another are caused to permanently adhere to one another, i.e. they are blocked. Then the cover 6 and the carcass 2 enclosed therein can be conveyed to an intermediate store 13.

The slats 8 can be provided with heating means so that the upper end of the cover 6 after evacuation can be 5 heat-sealed in substantially stretched-out condition above the carcass 2 and around the strap 4 which then preferably consists of material heat-sealable against the material of the cover 6. The heat sealing or welding is performed at a temperature higher than the temperature which is necessary 10 and utilised for blocking and making the cover shape per¬ manent.

Alternatively, the cover 6 can be sealed by the blocking of the interengaging surfaces of the upper part of the cover 6, in which case the stretching unit 7 is 15. carried along into the. heating cabinet 12. If, on the other hand, the upper end of the cover 6 is heat-sealed immediately after the air has been evacuated, the stretch¬ ing unit can be removed from the cover 6 before this is introduced into the heating cabinet 12. 0 The preferred embodiment, shown in Fig. 2, of the in¬ stallation according to the invention comprises the over¬ head conveyor 1 with the hooks 3 for carrying the car¬ casses 2 via the loop-shaped strap 4. The carcasses 2 ar¬ rive at the starting point of the conveyor 1 on a second 5 conveyor 14 on which the carcasses are carried by second hooks 15. At the junction of the first conveyor 1 and the second conveyor 14, each carcass 2 is transferred from the second hook 15 to the hook 3 having the strap 4. Then, the plastic bag 6 is pulled by hand over the carcass 2 which 0 is then conveyed into a combined evacuating and heating cabinet 16 in which the stretching unit 7 and the two slats 8 and the tubular members 9 with the connecting air evacuation lines 11 are mounted. The air evacuation equip¬ ment 10 is mounted on top of the cabinet 16. 5 From a control desk 17, the evacuation equipment and the heating equipment of the cabinet 16 are controlled, as is the operation of doors 18 between open and closed posi¬ tions.

As in the installation shown in Fig. 1, the carcass 2 enclosed in the cover 6 is conveyed, after evacuation, blocking and, optionally, heat-sealing in the cabinet 16, along the conveyor 1 to the intermediate store 13.

On the side of the conveyor 1 which is opposite to the cabinet 16, a further evacuating and heating cabinet 16' is provided which is identical with the heating cabi- net 16 and, like the latter, can receive a carcass 2 en¬ closed in a plastic cover 6. By utilising both cabinets 16 and 16' , the carcass throughput capacity of the installa¬ tion can, of course, be increased considerably. The con¬ trol desk 17 can be used for controlling both cabinets 16 and 16' which, besides, can have some component parts in common.

The construction of the heating cabinet 16 and the equipment therein is shown in more detail in Figs. 3-6. Fig. 3 is a cross-sectional view of the cabinet 16 perpen- dicular to the longitudinal direction of the conveyor 1. From the conveyor 1, a side track 19 extends into the ca¬ binet 16. By means of a switching member 20 pivotal be¬ tween two positions, a hook 3 and a carcass 2 hanging therefrom can be switched from the conveyor 1 to the side track 19. The hook 3 and the carcass 2 enclosed in the plastic cover 6 can thus be introduced into the cabinet 16 to the position shown in Fig. 3 in which the rear side of the upper end of the cover 6 and the strap engage with the leading edge of the rear slat 8. A guide member 21 in- eluded in the side track 19 can then be pivoted through 90° into a position in which it is wholly outside the ca¬ binet 16. The outer slat 8 which, during the movement of the carcass 2 into the cabinet 16, is in an upper position shown by dash lines in Fig. 3, can be swung, after the guide member 21 has been swung out, down about a pivot pin 22 into a lower position in which its trailing edge urges the leading edge of the upper end of the cover 6 against the leading edge of the rear slat 8.

The rear slat 8 is formed with recesses which, after the slats 8 have been compressed, permit downward movement of the two tubular members 9 through the upper open end of the cover 6.

As will appear from Figs. 3 and 6, two partitions 24 are mounted on each side of the door opening 23 of the ca¬ binet 16, said partitions having along the front wall and the rear wall, respectively, of the cabinet 16 an elongate slot 25 which is normally closed by oppositely directed bristles 26. A tubular frame 27 extends around the inner side of the cabinet 16 and behind the partitions 24. The tubular frame 27 has a front and a rear tubular member 28 and 29, respectively, as well as two connecting tubes 30 and 31, respectively, interconnecting the ends of said tubular members 28, 29. Rollers 32 are mounted on the ends of the connecting tubes 30, 31 and guided on vertical rails 33 on the inside of the side walls of the cabinet 16. The tubular frame 27 is movable, by means of wire drive means 34 which are but schematically shown, between a lower position shown by full lines in Fig. 3 and an upper position shown by dash lines in Fig. 3. The tubular members 28, 29 are provided with spray nozzles 35, and the connecting tubes 30, 31 have connections to a flexible in¬ let hose (not shown) extending up into the upper part of the cabinet 16 and from there down to the outlet side of a pump 38 (Fig. 2), the inlet side of which is connected to a water tank 39. In Figs. 3-6 the water tank lies outside the drawing. A drain 40 in the bottom of the cabinet 16 leads to the tank 39.

The installation shown in Figs. 2-6 operates as fol¬ lows. After a carcass 2 has been transferred from the con¬ veyor 14 to the conveyor 1, a cover 6 is pulled from below up over the carcass 2 which is then moved into the cabinet 16 where the upper end of the cover 6 is fixed in the ex¬ tended state between the slats 8, and the evacuating tubu- lar members 9 are pushed down into the upper open end of the cover 6. The air evacuation equipment 10 is then ac¬ tivated from the control desk 17 and sucks the air out of the cover 6 under the supervision of the operator. When the evacuation has been terminated, but while the evacua¬ tion equipment is still activated, the doors 18 are closed from the control desk 17, whereupon the heating equipment of the cabinet 16 is activated. The pump 38 is started, and hot water is sprayed from the tank 39 out through the spray nozzles 35 in the form of a curtain against the cover 6 enclosing the carcass 2. While hot water is being sprayed from the nozzles 35, the tubular frame 27 is raised from the lower position shown by full lines in Fig. 3 into the upper position shown by dash lines in Fig. 3, thus forcing the plastic of the cover 6 to permanently assume the shape imparted to it by the evacuation. Furthermore, the cover surfaces in contact with one another are caused to permanently adhere to one another, i.e. they are blocked. During the final phase of the up- ward movement of the tubular frame 27, the evacuation via the tubular members 9 is discontinued.

When blocking has been terminated, the pump 38 is stopped, the tubular frame 27 is lowered into the initial position, the tubular members 9 are raised, and the front slat 8 is swung up into its upper position. During these operations which, like the spraying of hot water, are automatically controlled, cold air can be blown down through the cabinet 16 for rapid cooling of the cover 6 and the carcass 2. Finally, the doors 18 are opened, and the side track 19 is again connected into the conveyor 1, whereby the ready-wrapped carcass can be moved to the in¬ termediate store 13, and a new carcass 2 can be introduced into the cabinet 16.

It will be appreciated that a number of further modi- fications of the above-described embodiments of the inven¬ tion are conceivable within the scope of protection as de¬ fined by the appended claims. For example, the conveyor 1, as shown in Fig. 1, can be designed for introducing the carcasses 2 on one side of the heating cabinet 12, 16 and for discharging the car¬ casses on an opposite side of the same cabinet. The cold air for cooling the cover 6 and the carcass 2 may also be introduced through nozzles which, like the nozzles 35, are mounted on the frame 27. Alternatively, cooling can be carried out outside the heating cabinet 12, 16. As an alternative to the water curtain, a hot-water bath, hot air, steam, radiation heat, or a combination thereof, may be used for heating the plastic cover.

Claims

1. A method for packing a carcass prior to freezing, storage and/or transport, by pulling a bag-like plastic cover from below over the hanging carcass, and evacuating the enclosed air, c h a r a c t e r i s e d in that the plastic cover after evacuation is heated sufficiently, but only so far that it can be made to permanently assume the shape obtained by the evacuation, and to achieve blocking of the cover surfaces in contact with one another, i.e. to cause these surfaces to strongly adhere to one another or be laminated permanently and without shrinking.

2. A method as claimed in claim 1, c h a r a c - t e r i s e d in that the cover is closed by blocking of the surfaces of the upper part of the plastic cover which are in contact with one another.

3. A method as claimed in claim 1, c h a r a c ¬ t e r i s e d in that after the evacuation the upper end of the cover is heat-sealed in a substantially stretched- out condition above the carcass and about a carcass sus¬ pension means, said heat sealing being carried out at a temperature which is higher than the temperature used for the blocking and for making the cover shape permanent. -

4. A method as claimed in any one of claims 1-3, c h a r a c t e r i s e d in that hot water, hot air, steam, radiation heat, or a combination thereof, is used for heating the plastic cover_

5. A method as claimed in claim 1, c h a r a c - t e r i s e d in that the plastic cover is heated suc¬ cessively by means of a water curtain which is moved from below upwards.

6. Installation for packing a carcass prior to freez¬ ing, storage and/or transport, by pulling a bag-like plas- tic cover (6) from below over the hanging carcass (2), and evacuating the enclosed air, c h a r a c t e r i s - e d by an overhead conveyor (1) with suspension means (3) for each carcass for conveying the carcasses to an evacua¬ tion equipment (9-11) for a pulled-on plastic cover (6) and to a heating equipment (12) for heating the plastic cover after the evacuation to, but not beyond, a tempe- rature at which the plastic cover permanently assumes the shape imparted to it by the evacuation, and the cover sur¬ faces in contact with one another are blocked, i.e. caused to strongly adhere to one another or be laminated perma¬ nently and without shrinking.

7. An installation as claimed in claim 6, c h a ¬ r a c t e r i s e d in that the heating equipment (12) comprises a heating cabinet (12, 16) that can be closed about a carcass (2) in an evacuated plastic cover (6) .

8. An installation as claimed in claim 7, c h a - r a c t e r i s e d in that said heating cabinet (12, 16) operates on hot water, hot air, steam and/or radiation heat.

9. An installation as claimed in claim 8, c h a ¬ r a c t e r i s e d in that a plurality of spray nozzles (35) for hot water are arranged vertically movable within said heating cabinet (16).

10. An installation as claimed in any one of claims 6-9, c h a r a c t e r i s e d in that the evacuation equipment 9-11 comprises slats (8) for stretching-out the upper end of the cover (6) and closing it about at least one through passage for the evacuation.