Packaging apparatus and techniques for forming closure tops

• US 4,201,030 A
• Filed: 12/21/1978
• Issued: 05/06/1980
• Est. Priority Date: 08/05/1977
• Status: Expired due to Term

• Current Assignee: Mahaffy & Harder Engineering Co. (Pro Mach Group, Inc.)
• Original Assignee: Mahaffy & Harder Engineering Co. (Pro Mach Group, Inc.)
• Inventors: Mahaffy, Reid A., Mainberger, Walter A.
• Primary Examiner(s): McGehee, Travis S.
• Application Number:
  US05/971,997
• Time in Patent Office: 502 Days
• Field of Search: 53/432, 53/433, 53/510, 53/511
• US Class Current: 53/432
• CPC Class Codes: B65B 31/021 the containers or wrappers being interconnected

Abstract

Packaging apparatus for making vacuum or gas-filled packages of the type including a flanged cup-shaped receptacle with a closure film sealed to the flanges and stretched down into the cup to engage and press against the product. The apparatus comprises a first packaging station where the film is sealed to the cup flanges part way around the cup mouth; simultaneously the film is heated in pre-selected locations to soften it for subsequent stretching. In a subsequent station, the partially-completed package is placed in a vacuum chamber and evacuated. Thereafter, a plug is driven against the still heated film, to force it down into the cup interior adjacent the product. Before or after the plug movement, the film is fully sealed to the cup, to make a hermetically-sealed package. While the plug holds the film in its stretched condition, the spaces outside of the film are vented to apply fluid pressure to the film, to cause the film to conform closely to the product shape, and to match closely the contour of the cup.

Claims

1. Packaging apparatus for making vacuum or gas-filled packages, comprising:

first and second packaging stations;

conveyor means for carrying a series of flanged cups into said second station, said cups containing products with upper surfaces thereof below the cup flanges;

means to supply a web of packaging material for movement through said first and second station with said web being positioned over said cups in said second station to serve as closure tops therefor to define packages;

heating means in said first station for supplying heat to said web of packaging material in preselected areas thereof to soften said web for subsequent stretch-forming in said second station;

vacuum means comprising a vacuum chamber at said second station to receive said packages, said vacuum chamber being shiftable from open to closed condition to evacuate said packages;

plug means in said second station;

drive means operable after said chamber has been closed for evacuation, said drive means serving to move said plug means relative to said vacuum chamber down against said heated web to stretch-form that web down into the interior of the corresponding cup, said plug means serving during evacuation of said chamber to force said web to a position at least immediately adjacent the upper surface of the product across substantially the entire upper surface thereof; and

means to pressurize at least substantially to atmospheric pressure the portion of said vacuum chamber above said web of packaging material to complete the formation of said closure top by developing a tightly-fitted, substantially void-free product-engaging contact between said web and said product.

2. Apparatus as in claim 1, including adjustable means to drive said plug means into the cup interior to the extent that the closure top reaches the adjacent surface of the product.

3. Apparatus as in claim 1, wherein said vent means is operable while said plug means is maintained in position holding said closure top stretched down into the cup.

4. Apparatus as in claim 1, wherein said vacuum means is operable to begin evacuation of said package prior to the actuation of said plug means to stretch-form said closure top down into said cup.

5. Apparatus as in claim 1, including planar heat-insulating means in said second station located closely above the plane of said web to prevent significant upward movement of said web during the evacuation of the package.

6. Apparatus as in claim 5, wherein said insulating means includes the planar surface of said plug means.

7. Apparatus as in claim 1, including means to heat said plug means so that heat is transferred to said upper web as it is stretched down into the cup.

8. Apparatus as in claim 1, wherein said first station comprises a heated platen;

and

vacuum means for drawing said web into contact with said platen to transfer heat to said web.

9. Apparatus as in claim 8, wherein said vacuum means comprises holes through said heated platen.

10. Apparatus as in claim 8, wherein said conveyor means carries said cups into said first station together with said web of packaging material;

initial heat-seal means in said first station; and

means to thermally isolate said initial heat-seal means from said heated platen.

11. Apparatus as in claim 1, wherein said vent means is operable to provide positive pressure to said web.

12. For making vacuum or gas-filled packages of the type wherein a film of packaging material, sealed to a flanged cup of packaging material containing the product, is stretched to extend into the cup in telescoping fashion to tightly grip the product within the cup;

the improved method comprising the following steps;

heating the film in regions thereof to be stretched into the cup;

placing the heated film and the cup in a vacuum chamber with the film overlying the cup flanges and the cup mouth to define a complete package;

closing said chamber to seal the interior thereof from outside atmosphere;

applying vacuum to said chamber and the interior of said package to initiate evacuation thereof;

after initiating evacuation of said sealed chamber and package, moving a plug against said film while it is still hot, to stretch-form the film down into the cup to a position at least immediately adjacent the upper surface of the product therein substantially over the entire upper surface thereof;

before or after said movement of said plug, sealing said package material to provide a complete hermetic seal of said package; and

pressurizing said vacuum chamber above said film to at least substantially atmospheric pressure while said plug is pressed against said film, the pressure forcing said film tightly against the product in said cup to effect close, intimate and essentially void-free contact therebetween.

13. The method of claim 12, including the step of admitting a gas into the package interior after the package has been evacuated;

thereafter hermetically sealing said package; and

thereafter moving said plug against said film.

14. The method of claim 12, wherein said plug is moved against said film prior to the hermetic sealing of said package and while said package is being evacuated, whereby the plug movement aids in evacuation of the package.

15. The method of claim 12, wherein said plug movement begins after start of evacuation of the package.

16. The method of claim 12, wherein said plug is moved a distance sufficient to stretch said film into contact with said product.

17. The method of claim 12, wherein said vent pressure is above atmospheric pressure.

18. The method of claim 12, including the step of transferring heat to said film during said plug movement.

19. The method of claim 18, wherein said heat is transferred to said film from said plug.

20. For making gas-filled packages of the type wherein a top film of packaging material is sealed to the flanges of a cup and the central regions of the film are stretched down into the cup interior to press against the upper surface of the product;

the improved method comprising;

positioning the film over the cup in the plane of the cup flanges to define a package structure;

evacuating said package structure and the spaces therearound;

admitting a predetermined amount of gas into said package structure;

hermetically sealing said film to said cup to make a complete package;

moving a plug against said film to force its central region into said cup to a position adjacent the product in the cup, thereby compressing the gas in the package; and

applying fluid pressure to said film to press that film tightly against said product.

21. The method of claim 20, wherein said fluid pressure is developed by venting the spaces above said film.

22. The method of claim 21, wherein said spaces are vented to a pressure above atmospheric.

23. Packaging apparatus for making vacuum or gas-filled packages, comprising:

first and second packaging stations;

conveyor means for carrying a series of flanged cups into said second station, said cups being formed with a predetermined plan configuration closely matching that of a product carried by the cup and having upper surfaces below the cup flanges;

means to supply a web of packaging material for movement through said first and second stations with said web being positioned over said cup in said second station to serve as closure tops therefor to define packages;

heating means in said first station for supplying heat to said web of packaging material in preselected areas thereof to soften said web for subsequent stretch-forming in said second station;

vacuum means comprising a vacuum chamber at said second station to receive said packages, said vacuum chamber being shiftable from open to closed condition to evacuate said packages;

plug means in said second station;

drive means in said second station operable after said chamber has been closed and during evacuation thereof to move said plug means forcibly down against said heated web to stretch-form that web down into the interior of the corresponding cup;

said plug means being formed with a plan configuration matching that of said cups and presenting a contact area at least substantially coextensive with the upper surface of the product in the cups so as to extend out laterally essentially to the side edges of said product adjacent the side walls of the cup;

adjustable means to control the depth of penetration of said plug means into each cup such that said web is forced down essentially substantially to the upper surface of the contained product; and

means to pressurize at least substantially to atmospheric pressure the portion of said vacuum chamber above said web of packaging material so as to complete the formation of said closure top after initial formation thereof by said plug means.

24. Apparatus as in claim 23, wherein the lateral dimensions of said plug means are substantially equal to the interior dimensions of said cup, to provide that the top as formed by said plug means extends out immediately adjacent to the inner side walls of the cup;

said plug means being formed at the sides thereof with sharply radiused edges to contact said web and provide sharp contours for the top.

25. For making vacuum or gas-filled packages of the type wherein a film of packaging material, sealed to a flanged cup of packaging material containing the product, is stretched to extend into the cup in telescoping fashion to tightly grip the product within the cup;

the improved method comprising the following steps;

heating the film in regions thereof to be stretched into the cup;

placing the heated film and the cup in a vacuum chamber with the film overlying the cup flanges and the cup mouth to define a complete package;

closing said chamber to seal the interior thereof from outside atmosphere;

moving a plug against said film while it is still hot;

while said plug is moving against said film, applying vacuum to said chamber and the interior of said package to effect evacuation thereof;

continuing the movement of said plug to stretch-form the film down into the cup to a position at least immediately adjacent the upper surface of the product therein, substantially over the entire upper surface thereof;

before or after said movement of said plug, sealing said packaging material to provide a complete hermetic seal of said package; and

pressurizing said vacuum chamber above said film to at least substantially atmospheric pressure while said plug is pressed against said film, the pressure forcing said film tightly against the product in said cup to effect close, intimate and essentially void-free contact therebetween.

26. Packaging apparatus for making vacuum or gas-filled packages, comprising:

first and second packaging stations;

conveyor means for carrying a series of flanged cups into said second station, said cups being formed with a predetermined plan configuration closely matching that of a product carried by the cup and having upper surfaces below the cup flanges;

means to supply a web of packaging material for movement through said first and second stations with said web being positioned over said cups in said second station to serve as closure tops therefor to define packages;

heating means in said first station for supplying heat to said web of packaging material in preselected areas thereof to soften said web for subsequent stretch-forming in said second station;

vacuum means comprising a vacuum chamber at said second station to receive said packages, said vacuum chamber comprising first and second mating components which are relatively shiftable from open to closed position to evacuate said packages;

plug means in said first component of said vacuum chamber and mounted for movement relative thereto towards and away from said packages;

drive means in said second station operable to move said plug means relative to said first chamber component and forcibly down against said heated web to stretch-form that web down into the interior of the corresponding cup;

said plug means being formed with a plan configuration matching that of said cups and presenting a contact area at least substantially coextensive with the upper surface of the product in the cups so as to extend out laterally essentially to the side edges of said product adjacent the side walls of the cup;

adjustable means to control the depth of penetration of said plug means into each cup such that said web is forced down essentially substantially to the upper surface of the contained product; and

means to pressurize at least substantially to atmospheric pressure the portion of said vacuum chamber above said web of packaging material so as to complete the formation of said closure top after initial formation thereof by said plug means.