US3895475A

US3895475A - Method and apparatus for vacuum skin packaging of soft meat and the like

Info

Publication number: US3895475A
Application number: US462035A
Authority: US
Inventors: Robert O Wolfelsperger
Original assignee: Individual
Current assignee: Individual
Priority date: 1974-04-18
Filing date: 1974-04-18
Publication date: 1975-07-22
Anticipated expiration: 1992-07-22

Abstract

This invention pertains to improvements in the method and apparatus for vacuum skin packaging such as is shown in U.S. Pat. No. 3,491,504 issued on Jan. 27, 1970. In the present invention a movable intermediate plate member is adjustably carried in the upper chamber half of the vacuum chamber. This movable member is adjusted prior to closing of the chamber so that in the ''''chamber closed'''' condition the intermediate plate member heats the upper film and maintains it close to the upper surface of the product which may be soft meat and products having a low profile such as bacon. The upper film is heated prior to the vacuum forming of the package which enables the film to be formed and sealed without compressing the product. In particular, the package produced by this method and apparatus accommodates products which may have bony sections such as lamb chops.

Description

United States Patent [191 Wolfelsperger July 22, 1975 METHOD AND APPARATUS FOR VACUUM SKIN PACKAGING OF SOFT MEAT AND THE LIKE [75] Inventor: Robert O. Wolfelsperger, Fairfield,

[73] Assignee: William E. Young, Atlantic Highlands, NJ.

[22] Filed: Apr. 18, 1974 [21] Appl. No.: 462,035

[56] References Cited UNITED STATES PATENTS 8/1965 Randall 53/86 1/1972 Pasco et al... 53/22 A Primary ExaminerTravis S. McGehee Attorney, Agent, or Firm-Ralph R. Roberts [5 7] ABSTRACT This invention pertains to improvements in the method and apparatus for vacuum skin packaging such as is shown in US. Pat. No. 3,491,504 issued on Jan. 27, 1970. In the present invention a movable intermediate plate member is adjustably carried in the upper chamber half of the vacuum chamber. This movable member is adjusted prior to closing of the chamber so that in the chamber closed condition the intermediate plate member heats the upper film and maintains it close to the upper surface of the product which may be soft meat and products having a low profile such as bacon. The upper film is heated prior to the vacuum forming of the package which enables the film to be formed and sealed without compressing the product. In particular, the package produced by this method and apparatus accommodates products which may have bony sections such as lamb chops.

6 Claims, 12 Drawing Figures METHOD AND APPARATUS FOR VACUUM SKIN PACKAGING OF SOFT MEAT AND THE LIKE BACKGROUND OF THE INVENTION 1. Field of the Invention In accordance with the classification of art as established in the US. Patent Office this invention pertains to the general Class of Package Making (Class 53) and more particularly to the subclass of packages wherein the contents are treated with vacuum or inert atmosphere (subclass 22). This method of packaging and the apparatus for performing the method pertain to the packaging of a product in a hermetically sealed package.

2. Description of the Prior Art Packaging of food products in thermoplastic film and with the packaged product brought to a condition of partial vacuum is, of course, well known in the art and the broad concept of forming a package in or with the assistance of vacuum is also well known. The packaging provided by patents directed toward the packaging of pharmaceutical products, food products such as processed sliced meats, cheeses and the like are directed mainly toward solid products and the resulting package and enclosed product are not distorted or deformed in the presence of vacuum.

In the present invention there is provided an improved apparatus and method for forming a skin package in which the product to be packaged may be relatively soft in nature. This apparatus may also be used for products having low and/or irregular profiles. Such products include chopped meat, a combination of meat items such as cubed meats on skewers, lamb chops or sliced bacon. This improved method and apparatus is used in conjunction with a method and apparatus such as is shown in US. Pat. No. 3,491,504 as issued to W. E. YOUNG etal. and is made without weakening the film used to enclose such products.

SUMMARY OF THE INVENTION This invention may be summarized at least in part with reference to its objects.

It is an object of this invention to provide, and it does provide, a method and apparatus for the film wrapping of soft products or low profile products in the presence of vacuum without distorting the product or tearing the film.

It is an object of this invention to provide, and it does provide a method and apparatus for limiting and controlling the expansion of a heated thermoplastic film as a closed chamber is brought to a condition of reduced pressure and while the upper film is in a heat softened condition.

It is yet another object of this invention to provide, and it does provide, a method and apparatus wherein the heated thermoplastic film is so retained during the package forming step that the amount of wrinkles or fins in the packaging material is qualitatively and quantitatively controlled.

As hereinafter more fully described, the improved method and apparatus for skin packaging of soft products and products with low profile includes a vacuum chamber having an upper and lower half which are separable. The chamber has an upper heated platen and a lower heated platen and there is provided a passage for evacuating the product area at a controlled rate.

LII

This upper chamber half includes an intermediate plate member which may or may not contain the heating element used within the upper chamber. This intermediate plate member is adjustable in height and prior to closing the chamber is adjusted so that in closed condition this plate member is brought into close proximity to the top of the product. or into slight contact with the top film. The plate member is usually heated to warm the upper film so as to easily conform to the product. The upper plate and the passageway between the films are selected to prevent excessive ballooning during evacuation of the chamber after which the package is tightly formed around the product.

In addition to the above summary the following disclosure is detailed to insure adequacy and aid in understanding of the invention. This disclosure, however, is not intended to prejudice the inventive concept no matter how it may later be disguised by variations in form or additions of further improvements. For this reason there has been chosen a specific embodiment of the method and apparatus for vacuum skin packaging as adopted for use in packaging soft meat and low profile products and showing a preferred means for carrying in the upper chamber half an intermediate plate member. This specific embodiment has been chosen for the purposes of illustration and description as shown in the accompanying drawing wherein:

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a sectional view of the chamber in a separated condition with the soft product carried on the lower web or film and in position prior to the closing of the chamber;

FIG. 2 is a sectional view of the chamber of FIG. 1 in its closed condition and prior to the evacuation of the chamber;

FIG. 3 is a sectional view of the closed chamber and showing the movement of the upper film at the initial stage of chamber evacuation;

FIG. 4 is a sectional view of the closed chamber with the package in its formed position after atmosphere or low pressure gas or air has been admitted to the upper portion of the chamber, this admitted pressure moving the film into a tightly wrapped condition around the product and the peripheral films into a hermetic seal;

FIG. 5 is a sectional view of the closed chamber similar to that of FIG. 3 and showing the movement of the upper film at the initial stage of chamber evacuation when the product has a low profile;

FIG. 6A represents a diagrammatic side view of a package such as in FIG. 2 and showing the deforming of the soft product when the upper film has not been sufficiently softened;

FIG. 68 represents a diagrammatic side view of the package of FIG. 6A but with the upper film sufficiently softened to readily conform to the product;

FIG. 6C represents a diagrammatic side view of the package of FIG. 6B but with the passageway between the upper and lower films restricted to an extent that ballooning of the film occurs and the resulting package has wrinkles;

FIG. 7A represents a side view of a package in which skewered meat and vegetables are wrapped as for shish-kabob;

FIG. 78 represents a sectional view of the package of FIG. 7A, this view taken on the line 78-73 and looking in the direction of the arrows;

FIG. 8A represents a side view of a package containing a lamb chop with a portion of exposed bone, and

FIG. 8B represents a sectional view of the package of FIG. 8A, this view taken on the line 8B8B and looking inthe direction f the arrows.

In the following description and in the claims various details are identified by specific names for convenience, these names, however, are intended to be generic in their application. Corresponding reference characters refer to like members throughout the several figures of the drawings. 7 The drawings accompanying this application disclose certain details of construction for the purpose of explanation but it should be understood that these structural details may be modified in various respects without departure from the concept of the invention.

CHAMBER ARRANGEMENT OF FIG. 1

Referring now to FIG. 1, there is depicted the chamber halves in a chamber open condition wherein a soft meat product 10 is carried on a lower web of film 11. Moving concurrently with the product 10 and film 11 is a top web of film 12 which may have been immediately previously heated by web heating means such as shown in the reference patent. In this warmed condition the top film web 12 is draped over the product 10 which as it is carried on the lower web 1 1 is supported on a lower heated platen 13. This platen is carried on a piston rod 14, which rod is slidably movable up and down in guides provided in the lower half or member of the chamber. This lower half is identified as 15. Aligned with and movable toward the lower chamber half 15 is an upper chamber shell or half 16. An intermediate andadjustable platen 18 is carried in and by shell 16.

Platen 18 is shown as having heating elements 19 therein and as being carried on and by a rod 20 slidably mounted in a vertical passageway formed in the upper chamber shell 16. A collar 22 engages rod 20 to retain this platen 18 at the desired vertical position in the upper half 16. A seal ring 23 prevents unwanted flow of air along rod 20 to the interior of the chamber. The upper film12 is advanced and retained in the desired draped position by

chains

24 and 25 by apparatus such as more fully described in the reference patent.

CLOSED CHAMBER OF FIG. 2

Referring next to FIG. 2, there is depicted the upper half shell 16 lowered to seat on lower half shell 15 and form a closed chamber generally identified as a vacuum chamber 28. Rib portion 29 has pushed the top web into a retained condition adjacent to but not in closing engagement with bottom platen 13. The upper film is now heated to a quite soft condition.

APPLIED VACUUM TO CHAMBER OF FIG. 3

Referring next to FIG.3, there is depicted the components of the vacuum chamber of FIG. 2 in the closed condition and it is to be noted that the lower platen 13 prior to closing the chamber is lowered to provide a upper surface of the product to be packaged and provides the desired final amount of heat to the upper web of film 12 to bring it to a sealing condition. Like heating is provided lower film 11 which is heated by lower platen 13. It is to be noted that the portion of the upper web 12 which extends from platen 18 to rib portion 29 is depicted as in a slightly ballooned condition. This condition arises by controlling the size of the passageway 30 so that the area 34 in which is contained the product does not give up its air as rapidly as does the upper chamber portion 36 which is above film 12. Vacuum is continued until the product 10 is brought to or substantially to the vacuum level of the chamber.

PACKAGE FORMING OF FIG. 4

Referring next to FIG. 4, the components of the chamber are still represented in an assembled condition, however, vacuum to the chamber has been shut off and atmosphere or low pressure air is fed to the interior of the chamber through passageway 32. Ator about the same time as the vacuum cycle was terminated, the lower platen 13 is raised to cause a restriction if not a complete closing of the passage at 30. The atmospheric pressure causes the heated upper web of film 12 to be moved into a tightly wrapped condition around the product 10 and this pressure differential causes the films to be pressed together to cause a seal of the upper web or film 12 and the lower film 11.

ALTERNATE PACKAGE OF FIG. 5

Referring next to FIG. 5, there is depicted the closed chamber of FIG. 3 but the product illustrated is a low profile product such as lunch meat or bacon. To prevent excessive ballooning the upper platen 18 is adjusted so that it is in close proximity to the top of product 110 and the amount of upper film web 12 subject to ballooning is minimal.

PACKAGES OF FIGS. 6A AND 6B In FIGS. 6A and 6B is shown a diagrammatic sectional view of a soft meat package. In FIGS. 6A the product 210 has an upper film l2 laying thereon. If this film is not sufficiently softened to readily accommodate itself to the contours of the product, the exertion of atmospheric air, as depicted by the small arrows, causes the outer upper corner portion of the product to be driven downwardly as represented by the dashed cross hatched area 213. The upper film 12 in FIG. 6A has been moved downwardly as indicated by the dashed outline.

In FIG. 6B the product 210 although as soft as that in FIG. 6A is not driven downwardly or distorted. Upper film 12 is heated to a softened, easily moved condition. This enhances its ability to be sealed. As depicted, this softened film is moved onto and around the.

product by atmospheric air as indicated by the several small arrows. This film while in a warmed state is easily stretched around the product without deforming the product. As the film engages the product it is cooled by the product to a non-stretching temperature and at this cooler temperature conforms to and tightly engages the product. In this manner the upper film is caused to move to provide the desired contour.

In FIG. 6C the warmed upper film 312a is shown in a slightly ballooned condition which is caused by opening 30 being too restrictive. Where and when opening 30 is insufficient the volume area 34 under the upper film 312a is unable to reach the condition of reduced pressure at about the same rate and time as the upper chamber area 36. As atmospheric air begins to urge the upper film toward the lower platen 13, the film instead of being taut is in a loose wrinkled condition as indicated in dashed outline 31217. When the upper film reaches the sealed condition of 312C the wrinkles persist and often make an unsatisfactory seal and do make an unsatisfactory package. For this reason the area of the opening 30 is selected in accordance with the area of the outer passageway 38.

PACKAGE OF 7A AND 7B Referring next to FIGS. 7A and 78, there is depicted a package which by conventional methods is difficult to satisfactorily and completely wrap. Skewered meat, with or without other ingredients such as vegetables used with shish-kabob, usually has wire or rod portions extending from the skewered items. Practice of the present invention in wrapping such items provides a satisfactory sealed package. The several products 410 are skewered on pointed metal member 80 and placed on lower film 11 which rests on the lower platen 13. As above discussed with respect to FIG. 6B, the upper film 412 is heated so as to be very easily moved to and around the product. As the film engages the product it is cooled by contact with the product and further stretching ceases. The resulting package is exemplified in the sectional view FIG. 7B. Note that the upper film is drawn around the metal member 80.

PACKAGE AS IN FIGS. 8A AND 8B Referring finally to FIGS. 8A and 8B wherein is depicted a package like the package of FIGS. 7A and 7B, the package of FIGS. 8A and 8B shows a product having an exposed bone portion which must be wrapped. A chop (lamb, pork, veal, etc.) 510 has a bone portion 510a which has been cleaned according to certain preparation customs. The chop is placed on lower film 11 and with the upper film 512 warmed so as to be easily drawn to and around the product 510 the bone portion 510a is covered by the upper film 512 as seen in FIG. 8B and in accordance with the above-described teaching.

USE AND OPERATION OF THE APPARATUS AND METHOD This invention pertains to the packaging of a multiplicity of products of like size and characterized in that they may be soft, have a low profile or have differential of components making wrapping by film very difficult. Each package is of a more-or-less determined size or height. During package forming it is essential that the passageway 30 be kept in an open condition during the bringing of all portions of the chamber to a condition of reduced pressure.

In operation the product is placed on a lower web of theremoplastic film l 1 such as Surlyn (Trademark of E. I. DuPont), Iolon (Trademark of E. I. DuPont) or a structured film having scalable surfaces. This film is carried in successive steps toward and onto lower platen 13 in the lower half chamber portion 15. At the same time the upper web of thermoplastic film 12, which also is preferably of Surlyn or Iolon, is heated by the heated upper platen 18. This top film 12 which is a strip or web is moved by

chains

24 and 25 toward and into the vacuum chamber and over product 10. This product 10 is now between the two webs of film with the upper film 12 draped over the product 10 which rests on the bottom web 11 as shown in FIG. 1.

The upper chamber half 16 is lowered to meet the lower chamber half 15 and with appropriate closing pressure and sealing means provides the vacuum chamber 28 as shown in FIG. 2. The lower heated platen 13 whose heat is regulated by a conventional temperature controlling means has been previously lowered into the lower chamber 15 to provide the arrangement as seen in FIGS. 2 and 3, and the interior of the chamber is connected to a source of vacuum with the flow of air in the chamber moving through passageway 32 as indicated by the arrow in FIG. 3.

Whether the product to be packaged is soft meat, a low profile product or a dissimilar product such as a chop, a minimum of distortion to the packaged product 10 is desirable. It is necessary to heat the upper web of film 12 by the heating means to such a degree that it is very pliable. When the film is very soft the film has a tendency to sag with the outer portions of film l2 draping toward the lower platen 13 and resulting in a restriction to the flow of air toward the source of vacuum which occurs at the peripheral passageway 30 during the evacuation of the chamber 28. This restriction at passageway 30 causes that inside space or area 34 between film 12 and the product 10, as seen in FIG. 3, to be evacuated at a slower rate than the outside space or area 36 in the upper chamber half and above film 12. Unless the passageway 30 is accordingly increased the resulting differential of pressure between the inside space 34 and the outside space 36 causes the now very pliable upper web of film 12 to balloon. This is shown in FIGS. 3 and 6C in which is created an excessive extent of film 12. Excessive overstretching of film results in a package having wrinkles or fins in the sealed area of the package as in FIG. 6C.

It is also to be noted that as the intermediate platen 18 is heated to add additional heat to that warmed upper film 12 within the chamber a much lower temperature is required with and by the web heating means 19 to heat the upper web of film 12 prior to closing the chamber thereby virtually eliminating a sagging of the upper web of film 12 prior to the connection of the closed chamber to vacuum.

The intermediate heated platen 18 is slidably adjustable in the upper half of the chamber 16 and is adjusted so as to be positioned to limit any upward ballooning action of the upper web of film 12 during evacuation of the chamber 28 and product 10 as and when a differential pressure between

area

34 and 36 occurs during the forming of the package around a product 10. Unwanted or accidental adherence of film 12 to the intermediate heated platen 18 is avoided by coating this platens lower face with a release material such as Teflon (Trademark of DuPont) or the like. An additional benefit derived by heating the intermediate upper platen 18 is that because of close proximity, heat is transferred rapidly and uniformly to the upper web 12. This supplements the initial heating which has been lost during the skin packaging cycle. After the vacuum cycle is completed and as seen in FIG. 4, the lower heated platen 13 is raised to restrict or close the passageway 30. With the vacuum now shut off, immediately thereafter or substantially at the same time, conduit 32 is opened to atmosphere or positive pressure which is fed to the outside chamber area 36. This atmosphere or positive pressure as depicted in FIG. 6B exerts a force on the upper web of film 12 and urges this film into a skintight condition around the product with out causing an appreciable amount of deformation of the product. It is to be noted that moving the lower platen is a preferred means for closing passageway 30 but alternate means such as a separate valved inlet could be provided. When such an arrangement is made the lower platen could be fixed as to vertical movement.

As also occurs in reference U.S. Pat. No. 3,491,504, the upper web of film 12 which is exterior of the product is pressed by the atmosphere into a sealing condition with lower heated film 11. After this scaling is achieved the chamber is opened, the packaged product is separated and removed with the surplus film removed by conventional trimming apparatus.

As depicted in FIG. 5, this invention solves the problem of vacuum skin packaging of low profile products 110. The retaining of the film in close proximity to the top surface of the product prevents the ballooning of the softened film during the initial connecting of the chamber to vacuum. The unwanted wrinkles caused by stretching of the film as in FIG. 6C is thus avoided and by using the adjustable intermediate upper platen tight films on vacuum packaged products is the desired result. As depicted in FIGS. 7A, 7B, 8A and 83, this method of packaging also solves the problem of packaging items having dissimilar portions.

Although directed to a specific problem found in packaging soft meat products, low profile products and dissimilar components, the present invention does solve the problems which developed in the automatic packaging of products in accordance with the teachings of U.S. Pat. No. 3,491,504. A satisfactory tight wrap of the product must include a complete seal of the two films to each other absent leaks caused by wrinkles which occur because of overstretching of the film. This overstretching is eliminated in the present method and by the disclosed apparatus by which the method may be practiced.

Terms such as up, down, bottom, top, in, out and the like are applicable to the embodiment shown and described in conjunction with the drawings. These terms are merely for the purpose of description and do not necessarily apply to the position in which the vacuum chamber with adjustable intermediate upper platen may be constructed or used.

While a particular embodiment of the apparatus has been shown and described it is to be understood modifications may be made within the scope of the accompanying claims and protection is sought to the broadest extent the prior art allows.

What is claimed is:

1. Apparatus for vacuum skin packaging a product such as soft meat, a low profile product, a product having dissimilar portions and like products, the wrapping being under the influence of vacuum requiring at least a short period of time to be brought to a condition of reduced pressure, the apparatus including: (a) a lower chamber half; (b) a lower platen carried in this lower chamber half and providing therewith and thereon an upper surface means for placing and supporting a product; (0) means for delivering and positioning on the lower platen support surface a lower film and subsequent to said positioning means for placing on said lower film a product to be wrapped; (d) an upper chamber half having a lower sealing means compatible with an upper surface of the lower chamber and when the upper chamber is brought to a seating condition with and on the lower chamber half a substantially vacuum tight chamber is provided; (e) an upper film web selectively transported and positioned by means adapted to drape this upper film web over the product and in and after so draping bringing the outer portions of the web into a retained condition on the lower chamber half so that a communication pathway is provided between the draped upper film web and the lower film, this pathway insuring that the product is subject to the same environmental condition as that provided in the interior of the sealed chamber; (f) means for guiding the upper film transport and enclosing the transport so that during the period of closing of the upper and lower chamber portions the film transport is sealed from the interior of the chamber; (g) a movable intermediate plate member carried by and in the upper chamber half; (h) means for moving this plate member so that as and when the upper chamber is brought into a seated condition, the intermediate plate member is brought into a fixed position to provide a retaining condition of that upper web of film which is above the product so as to maintain this film in an immediate proximity to the product absent further movement of the plate toward the product and thus positioned prevent excessive ballooning and stretching of this upper film during evacuation of the chamber and product; (i) means to bring the closed chamber and product to a condition of reduced pressure; (j) means to bring the peripheral portions of the upper and lower films to a condition for sealing to each other; (k) means for closing the communication pathway between the upper and lower films and to the product, and (1) means for opening the interior of the evacuated chamber to atmosphere, pressurized gas and the like so as to press the peripheral portions of the upper and lower films into a sealed condition and thereafter opening the chamber for removal of the packaged product.

2. Apparatus for vacuum skin packaging as in claim 1 in which the upper and lower films are thermoplastic and amenable for heat sealing to each other and the lower platen and intermediate platen have means for heating and maintaining said films to a heat sealing condition.

3. Apparatus for vacuum skin packaging as in claim 2 in which the upper film prior to evacuation of the closed chamber is in a heat softened condition to enable a tight packaging to the product to be achieved and the intermediate platen is of a sufficient extent to retain all that portion of the upper web above the product in close proximity to the upper portion thereof and the intermediate platen is of sufficient further extent to inhibit heat softened upper film which provides the sloped unrestrained drape of this upper film from excessive ballooning as and when the product is brought to the condition of reduced pressure.

4. Method for vacuum skin packaging of a product such as soft meat, a low profile product, a product of dissimilar portions and the like, the packing steps requiring the product portion to be brought under the influence of vacuum for at least a short period of time to achieve a condition of reduced pressure, this method including the steps of: (a) providing a chamber having upper and lower halves with the lower half having a platen on which there is formed an upper surface means for supporting a product; (b) delivering and positioning on this lower platen support surface a lower film and subsequent to positioning the lower film placing thereon a product; providing on the upper chamber half a lower sealing means compatible with an upper surface of the lower chamber and when the upper chamber is brought to a seating condition with and on the lower chamber half establishing a substantially vacuum-tight chamber; (d) transporting and positioning an upper film web by means adapted to drape this upper film web over the product and in and after so draping bringing the outer portions of the web into a retained condition on the lower chamber half and establishing therewith a communication pathway between the draped upper film web and the lower film, this pathway insuring that the product is subject to .the same environmental condition as that provided in the interior of the sealed chamber; (e) forming and providing an upper film transport having enclosing means so formed and positioned that during the period of closing the upper and lower chambers portions of the film transport is sealed from the interior of the chamber; (f) moving this plate member so that as and when the upper chamber is brought into a seated condition, the intermediate plate member is brought into a fixed position providing therewith a retaining condition of that upper web of film which is above the product to maintain this film in immediate proximity to the product and absent further movement of the plate toward the product therewith and thereby preventing unwanted and excessive ballooning of the upper film during the evacuating of the chamber and the product; (g) bringing the closed chamber and product to a condition of reduced pressure by connecting same to a vacuum producing source; (h) bringing the peripheral portions of the upper and lower films to a condition for sealing to each other; (i) closing the communication pathway between the upper and lower films and to the product, and (j) shutting off the source of vacuum to the chamber and opening the interior of the evacuated chamber to atmosphere, pressurized gas and the like and with the resulting pressure differential one the exterior of the upper film pressing the peripheral portions of the upper and lower films into a sealed condition and thereafter opening the chamber and removing the packaged product.

5. The method of vacuum skin packaging as in claim 4 in which the upper and lower films are thermoplastic and amenable for heat scaling to each other and includes the step of providing in the lower platen means for heating said films to a heat sealing condition.

6. The method for vacuum skin packaging as in claim 5 which includes the further step of heating the upper film prior to evacuation of the closed chamber to bring said web to a heat softened condition to enable a tight packaging to the product to be achieved and the further step of forming the intermediate platen so as to have a sufficient extent to retain all that portion of the upper web above the product in close proximity to the upper portion thereof and the intermediate platen is of sufficient further extent to inhibit the heat softened upper film which provides the sloped unrestrained drape of this film from excessive ballooning as and when the product is brought to the condition of reduced pressure.

Claims

2. Apparatus for vacuum skin packaging as in claim 1 in which the upper and lower films are thermoplastic and amenable for heat sealing to each other and the lower platen and intermediate platen have means for heating and maintaining said films to a heat sealing condition.
3. Apparatus for vacuum skin packaging as in claim 2 in which the upper film prior to evacuation of the closed chamber is in a heat softened condition to enable a tight packaging to the product to be achieved and the intermediate platen is of a sufficient extent to retain all that portion of the upper web above the product in close proximity to the upper portion thereof and the intermediate platen is of sufficient further extent to inhibit heat softened upper film which provides the sloped unrestrained drape of this upper film from excessive ballooning as and when the product is brought to the condition of reduced pressure.
4. Method for vacuum skin packaging of a product such as soft meat, a low profile product, a product of dissimilar portions and the like, the packing steps requiring the product portion to be brought under the influence of vacuum for at least a short period of time to achieve a condition of reduced pressure, this method including the steps of: (a) providing a chamber having upper and lower halves with the lower half having a platen on which there is formed an upper surface means for supporting a product; (b) delivering and positioning on this lower platen support surface a lower film and subsequent to positioning the lower film placing thereon a product; (c) providing on the upper chamber half a lower sealing means compatible with an upper surface of the lower chamber and when the upper chamber is brought to a seating condition with and on the lower chamber half establishing a substantially vacuum-tight chamber; (d) transporting and positioning an upper film web by means adapted to drape this upper film web over the product and in and after so draping bringing the outer portions of the web into a retained condition on the lower chamber half and establishing therewith a communication pathway between the draped upper film web and the lower film, this pathway insuring that the product is subject to the same environmental condition as that provided in the interior of the sealed chamber; (e) forming and providing an upper film transport having enclosing means so formed and positioned that during the period of closing the upper and lower chambers portions of the film transport is sealed from the interior of the chamber; (f) moving this plate member so that as and when the upper chamber is brought into a seated condition, the intermediate plate member is brought into a fixed position providing therewith a retaining condition of that upper web of film which is above the product to maintain this film in immediate proximity to the product and absent further movement of the plate toward the product therewith and thereby preventing unwanted and excessive ballooning of the upper film during the evacuating of the chamber and the product; (g) bringing the closed chamber and product to a condition of reduced pressure by connecting same to a vacuum producing source; (h) bringing the peripheral portions of the upper and lower films to a condition for sealing to each other; (i) closing the communication pathway between the upper and lower films and to the product, and (j) shutting off the source of vacuum to the chamber and opening the interior of the evacuated chamber to atmosphere, pressurized gas and the like and with the resulting pressure differential one the exterior of the upper film pressing the peripheral portions of the upper and lower films into a sealed condition and thereafter opening the chamber and removing the packaged product.
5. The method of vacuum skin packaging as in claim 4 in which the upper and lower films are thermoplastic and amenable for heat sealing to each other and includes the step of providing in the lower platen means for heating said films to a heat sealing condition.
6. The method for vacuum skin packaging as in claim 5 which includes the further step of heating the upper film prior to evacuation of the closed chamber to bring said web to a heat softened condition to enable a tight packaging to the product to be achieved and the further step of forming the intermediate platen so as to have a sufficient extent to retain all that portion of the upper web above the product in close proximity to the upper portion thereof and the intermediate platen is of sufficient further extent to inhibit the heat softened upper film which provides the sloped unrestrained drape of this film from excessive ballooning as and when the product is brought to the condition of reduced pressure.