US 3688463 A
Improved bag constructions, and automatically operable methods and apparatus are disclosed for vacuum packaging various products that can be either regular or irregular in shape. The bag construction includes spreadable flaps adapted to be "plowed open" to assist in automatically filling the bags, and which are thereafter gripped and held in an extended, preferably substantially flat planar fashion during bag vacuumization and sealing. Apertures pre-cut in the flaps permit rapid vacuumizing cycles without need for probes, spreaders or the like to open the bags for evacuation. In addition, the bags can be formed of a wide variety of films, such as soft or alternately supported films, as desired.
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Description (OCR text may contain errors)
United States Patent Titchenal 1 Sept. 5, 1972  VACUUMPACKAGING SYSTEM 3,059,389 10/ 1962 Randall ..53/1 12 B X  Inventor: Oliver Titcheml, Berea, Ohio 3,430,414 3/1969 Ludwig et al ..53/1 12 B  Assignee: The Dow Chemical Company, Pn'mary Examiner-Travis S. McGehee Midland, Mich. Attorney-Gustalo Nunez  Filed: July 15, 1970  ABSTRACT  Appl. No.: 55,141
Related U.S. Applimtion Data Continuation-impart of Ser. No. 727,464, May 8, 1969, Pat. No. 3,559,874.
References Cited UNITED STATES PATENTS Royal ..5 3/ 22 B Improved bag constructions, and automatically operable methods and apparatus are disclosed for vacuum packaging various products that can be either regular or irregular in shape. The bag construction includes spreadable flaps adapted to be plowed open to assist in automatically filling the bags, and which are thereafter gripped and held in an extended, preferably substantially flat planar fashion during bag vacuumization and sealing. Apertures pre-cut in the flaps permit rapid vacuumizing cycles without need for probes, spreaders or the like to open the bags for evacuation. In addition, the bags can be formed of a wide variety of films, such as soft or alternately supported films, as desired.
11 Claims, 6 Drawing Figures PMENTEDSEP 51972 SHEU 2 0F 2 INVENTOR. 0/1'uer R. Tif h BMW. W
HTTORNEY VACUUM PACKAGING SYSTEM This application is a continuation-in-part application of my copending application Ser. No. 727,464, filed May 8, 1969, now U.S. Pat. No. 3,559,874.
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to improved bag constructions, methods and apparatus for automatically forming vacuum packages such as are applicable for containing cheese, luncheon meats, frankfurters, steaks, poultry or like products of a type that can be better stored in a vacuum or controlled gaseous environment. More particularly, the invention relates to such methods and apparatus employing preformed bag stock as the packaging means.
2. Discussion of the Prior Art Current practice is oftentimes to vacuumize preformed bags by inserting a nozzle into the mouth of the bag. Two techniques are commonly used. In one the operator tightly gathers the open end of the bag about the nozzle by hand pressure. The vacuum is then drawn through the nozzle, and subsequently the bag is closed usually by clipping or tieing. In the second technique the bag is clamped between, for example, rubber lined jaws including nozzle means interposed between the jaws, and which communicate with the interior of the bag. Subsequent bag closure is usually by heat sealing.
Objectionably, neither practice has offered a fully satisfactory solution for automatically vacuumizing bags including automatic delivery and indexing of the bags to and from the vacuumizing station. For example, in both practices the nozzle is ordinarily in an interferring position with bag closure and, therefore, must be moved while retaining a vacuum environment within the bag. Moreover, the initial positioning of the nozzle within the bag, at rapid cycles, poses difiicult engineering problems added to by the fact that the bag must normally be sealed off from the atmosphere accompanying this step. Witness, therefore, the present reliance on an operator who manually gathers the bag about the nozzle by hand pressure; or the manual placement of the bag between reciprocally operated clamping jaws of sufficient resiliency to also accommodate the nozzle. Understandably, such manual functions are difficult for machine adaptations or substitutions and, therefore, difficult to fully automate as indicated.
A different approach to the problem has been to depart from use of vacuumizing nozzles, and instead use vacuumizing chambers in which the bags are evacuated and sealed closed. For example, in one prior art technique, a filled bag is placed in the chamber with the open end of the bag positioned between heat sealing jaws. The chamber is then evacuated allowing air to escape through the open end of the bag, and this is followed by a closure step wherein the jaws close to hermetically seal the vacuum environment within the bag. Difiiculties with this technique arise when attempting to rapidly index the bags into the chamber in proper positioning with relation to the heat sealing jaws. Past practice has generally required that this function be manually accomplished. Another disadvantage is that this technique usually requires the use of relatively stiff or supported film materials as opposed to the more soft or limp films for constructing the bag.
As pertinent background information, supported films are essentially structured films including a relatively stiff layer comprised of material such as cellophane, paper, polyethylene terephalate, metal foil, and certain formulations of, for example, nylon, polyvinyl chloride, and polypropylene. Laminated or coated to one side of the stiff layer or layers is a heat sealable material customarily comprising polyethylene, ethylene vinyl acetate copolymers and the like. A soft film, on the other hand, may be either a structured or single layered film as represented by a Saran/polyethylene structured film, or a polyethylene single layered film, for example.
It is among the objects of the present invention, therefore, to provide the following:
An improved system for forming vacuum packages from preformed bag stock;
Such a system wherein the filling operation is expediently accomplished, and can be readily mechanized;
A system wherein the vacuumizing portion of the apparatus operates without requirement of a vacuumizing nozzle, or without need for probes, spreaders or the like to open the bag for evacuation; and additionally, wherein the bags can be automatically indexed forward for evacuation and sealing of the same;
Such a system wherein the formation of the final closure seal is made with provisions to minimize the effect of wrinkles and/or distortions accompanying vacuumization of the bag;
A system of the general type indicated wherein preformed bags comprise the packaging means, and wherein the bags can be formed of supported, non-supported or soft films, as desired; and
Such a system wherein the bags are desirably connected together in generally side-by-side fashion to assist in providing overall economies and advantages heretofore not fully realized in vacuum packaging operations.
BRIEF SUMMARY OF THE INVENTION In the packaging system contemplated herein, a bag construction characterized as having opposed spreadable flaps associated with its open end or fill opening is used. Filling and sealing operations are desirably accomplished by employing continuous belts which receive and grip between them the flap portions (i.e., top ends) of such bags and controllably deliver the same to a filling station, and thereafter to a vacuumizing station. The filling station can comprise a hollow sleeve member fitted in between the belts, and adapted to plow open the bag flaps, thereby permitting mechanized filling of the bags through the hollow sleeve. The vacuumizing station can comprise a vacuum chamber of the type having first and second mateable halves which close about a group of filled bags to form a hermetically tight vacuumizing chamber thereabout. A port means or aperture is precut, for example, in the flap region of the bags permit rapid, but generally uncomplicated vacuumizing cycles, and the bags are subsequently sealed closed at a region inwardly of the port means such as by heat sealing or the like. The flaps are held extended during vacuumization, most conveniently between the lips of the vacuum chamber, so that a sufficiently wrinkle-free region is provided for a heat seal closure. The flaps can be subsequently trimmed, or used to form a handle for each bag. Most desirably, the bags are lightly connected together during filling, and then broken apart in groups along preformed lines of weakness therebetween for entry into the vacuum chamber. As will become evident thereinafter, such a system is applicable for total mechanization, if desired.
BRIEF DESCRIPTION OF THE DRAWINGS The preferred embodiment of the present invention is shown in the accompanying drawings in which wheresoever possible, like characters of reference designate corresponding material and parts throughout the several views thereof in which:
FIG. 1 is a side elevational view of a series of connected bag elements constructed according to the principles of the present invention;
FIG. 2 is a cross-sectional view of the bag elements of FIG. 1 taken along reference line 2-2 thereof;
FIGS. 3 and 4 are diagrammatic and schematic illustrations of the apparatus of the present invention as viewed from the top and side, respectively;
FIG. 5 is a partial enlarged end view of the vacuumizing station or module of the apparatus of FIGS. 3 and 4; and
FIG. 6 is an enlarged cross-sectional view taken along reference line 6-6 of FIG. 3.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring more particularly to the drawings, there is shown in FIG. 1 and 2, a chain or connected series of bag elements 10 of the general type adapted for use in the improved packaging system disclosed herein.
Bag elements 10 are desirably connected together along lines of weakness 12 comprising, for example, perforations 14 separated by lands or noncut regions 16. On each side of lines of weakness 12 are sealed regions or strips 18 and 20, respectively, which close bag sides 22 and 24 therealong. Strips l8 and 20 secure together the confronting walls 26 and 28 comprising each bag element, but terminate at a spaced distance from the top end portions 30 thereof, such as to leave freely spreadable flaps 32 and 34. Port means or apertures 36 are desirably precut in either or both flaps 32 and 34 at a region above strips 18 and 20. In other words, apertures 36 are positioned above, or alternately, above and adjacent to the enclosure portion 19 included in the bag element 10 structure. Most desirably, the uppermost extent 38 of flaps 32 and 34 are left continuously intact with lines of weakness l2 terminating prior thereto, for reasons as will become more evident hereinafter. The bottom ends 40 of bag elements 10 can be closed by a fold 38, or by a gusset, seam or like means as is conventional.
Bags 10 can be formed of barrier material such as saran (a vinylidene chloride vinyl chloride copolymer) coated on one side with a glue layer such as ethylene vinyl acetate copolymer; or laminated or co-extruded combinations of film such as of a type as illustrated in British Pat. No. 1,146,647, for example. Especially suitable for forming bag elements 10 are multi-ply films of a type commercially available from The Dow Chemical Company under the trade designation Saranex brand films. Unsupported Saranex brand films and saran films would be representative examples of so films applicable for forming bag elements 10. Normally the applicable gauge of such film would be in a range of approximately between half mil to 5 mils, depending mostly on bag size, and the type product to be packages therein. In any event, film gauges as are presently used in conventional packaging applications can be for the most part employed for constructing bag elements 10 without change, if desired. In other words, the present packaging system does not require bags formed of extra stiff or thick film, or films of the type generally characterized as supported films, and which are frequently employed in packaging because of their improved stiffness of handling characteristics. It is to be understood, however, that the present packaging system is equally able to handle supported as opposed to unsupported or soft films, such as where their use may be desired, for example, for reasons other than handling or package forming ease.
FIGS. 3 through 7 show schematically a bag filling and vacuumizing apparatus 46 including a first or filling module 48, and second or bag separating module 50. Generally speaking, separating module 50 receives filled bags from module 48, separates them along lines of weakness 12 into groups comprising one or more bags, and then transfers the same to a third or vacuumizing module 52.
Referring now specifically to filling module 48, the same comprises in part a horizontally inclined conveyor means or belt 54. A rigidly placed hollow shell or member 56 is located adjacent the near side of conveyor 54. Operating above and below shell member 56 are continuous gripping or pulley-like belts 58 and 60. Belts S8 and 60 are contacting substantially through the entire length of the adjacent or facing runs 62 and 64 thereof, except for the intermediate portion or runs 62 and 64 which snugly pass on each side 66 and 68, respectively, of the shell member (see FIG. 6).
A second horizontally inclined conveyor belt 70 is positioned in line with conveyor belt 54 and comprises a part of separating module 50. Also included is a second set or gripping or pulley-like belts 72 and 74 including contacting runs 76 and 78. Belts 72 and 74 are located generally in line with gripping belts 58 and 60 of the filling module, but are disposed in a region slightly inside of the same, and overlap with belts 58 and 60 for a short distance, as is denoted at region 80 (see FIG. 3). Such an overlap arrangement is desirably employed in other parts of apparatus 10 as indicated hereinafter, and with unsupported films avoids the possibility of the leading edge of the film from drooping and thereby improperly transferring between adjacent sets of belts.
In addition, bag separating module 50 desirably includes a film trimming device denoted schematically at 82, and which is positioned in an area slightly forward of overlapped region 80, and in alignment with the gap or spacing 84 between the first and second sets of gripping belts. Trimming device 82 can comprise, for example, a pair of peripherally sharpened, rotatably driven discs 86 and 88 which cooperatively afl'ect a continuous scissoring action; or alternately, the same can comprise a trimming tool such as a stationary blade or the like (not shown).
vacuumizing module 52 comprises a third set of gripping or pulley-like belts 90 and 92 set slightly inwardly of the second pair of gripping belts 72 and 74 and slightly overlapped therewith for reasons as explained generally hereinbefore. A hollow vacuumizing chamber 94 is positioned at the inward side of the third pair of gripping belts 90 and 92 directly in line with conveyor belt 70 of bag separating module 50. Chamber 94 preferably comprises a stationary lower half or part 96, and a movable upper part of half 98 operable from a closed position, as is denoted in full lines in FIGS. 3-5, to an open or article receiving position, as is shown in dotted lines in FIG. 5.
Inside chamber 94 is an internal conveyor belt 100 operably mounted in lower half 96. The back and forward edges of lips 102 and 104 of lower half 96 are recessed (see FIG. 5) to permit filled bags to be smoothly transferred from separating module 50 onto internal conveyor belt 100, and then subsequently delivered from the chamber to a feed-off conveyor belt 106, which receives the bags after the vacuumization and sealing thereof. The lateral side edges of lips 108 and 110 of lower half 96 are raised a sufficient extent so as to be substantially in horizontal planar alignment with the interface defined between the contacting runs 112 and 114 of gripping belts 90 and 92. This arrangement minimizes distortion of the bags as they enter and are processed in chamber 94, as will become evident hereinafter. Additionally, the lips of halves 96 and 98 will be customarily faced with suitable gasket material, as is denoted at 116 and 118, to affect a substantially hermetic seal upon closure of chamber 94.
Further, internal structure of chamber 94 includes cooperating sealing bars 120 and 122 located to one side of internal conveyor belt 94 at a region generally intermediate thereof and the adjacent sidewall of chamber halves 96 and 98. The lower sealing bar 120 is ordinarily rubber faced and can be rigidly mounted in lower half 96, if desired. The upper sealing bar 122 can be heated to sealing temperatures by suitable means (not shown) and can be movably operated such as by dual air cylinder means 124 which in turn, for example, can be affixed to upper half 98. Positioned adjacent the inward side of upper sealing bar 122 is a restraining rod or means 126 rigidly connected together at its ends, respectively, with upper half 96. In addition, tubing means (not shown) communicates between the interior of chamber 94 and a vacuum pump or like vacuumizing means for pulling a vacuum in chamber 94 in accordance with customary procedures.
OPERATION To operate apparatus 46, bag elements are preferably fed flatwise onto conveyor belt 54 from a folded pile, or alternately, can be fed from roll stock (not shown). Desirably, in feeding from a folded pile, the usual unwinding tensions associated with roll stock are avoided, and therefore the possibility of bags prematurely breaking apart along lines of weakness 12 is minimized. A related feeding arrangement from folded or piled bag stock, for example, is illustrated in some detail in co-pending US. Pat. application Ser. No. 816,588.
Assisting conveyor belt 54 with the initial infeed of bags 10 are the first pair of gripping belts 58 and 60 which receive between them the flap portion of the bag elements. Gripping belts 58 and 60 with conveyor belt 54 cooperatively forward the bags to sleeve member 56.
Accompanying their approach to sleeve member 56, flaps 32 and 34 are continuously plowed open by the leading edge 128 of the sleeve member, and pass about the opposite sides 66 and 68, respectively, thereof. Flap 32 is thus cooperatively held between side 66 and belt 58; and flap 34 between side 68 and belt 60 (see FIG. 6). Bags 10 are now ready to be filled one at a time, or if desired, in groups such as in groups of three, as is denoted in FIG. 3 by the group of bags designated as A. Filling can be accomplished manually if desired by an operator who would hand insert a product fill into the bags through sleeve member 56; or filling can be fully or semi-mechanized such as, for example, by utilizing a conventional push-pull filling mechanism (not shown).
In either event, following the filling step, the bags, still in connected form, are forwarded to a rest position comprising the downwardmost part of conveyor belt 54. During the next immediate indexing or filling cycle, the group of filled bags occupying the rest position, these being designated as group B, are transferred to separating module 50. Accompanying the latter transfer, the bags comprising group B are controllably separated from the chain as a unit along an appropriate line of weakness l2; namely, every third line of weakness for groups consisting of three bags. The separated group is then moved forward on conveyor belt toward vacuumizing module 52.
More specifically, such separation of the filled group occupying the rest position B, is conveniently accomplished in the next immediate forwarding cycle, for example, by driving gripping belts 72 and 74 continuously, and operating filling module 48 intermittently. Thus for filling groups of three bags, the chain of bags 10 is indexed forward three units. This, in turn, moves the leading three bags from the rest position B forward onto conveyor belt 70. The belts comprising filling module 48 then stop for a suitable filling interval, whereby the continuously operated belts comprising the filling module separate the leading group of three filled bags from the chain. It may be noted that the part of gripping belts 72 and 74 in the region denoted at 80, will desirably only lightly engage the bag material. In other words, the pressure, if any, between the contacting surfaces of runs 76 and 78 in region would ordinarily be somewhat lighter then in the more forward regions of belts 72 and 74. This would prevent an undesirable continuous pulling force on the filled group occupying the group B position during the stop interval accompanying filling. Pinch rolls 130 and 132 located downwardly of this latter position can be employed to supplement the pulling force of belts 72 and 74, if desired.
To assist separation of the filled group at separating module 50, trimming device 82 operates to remove approximately that portion of film between the terminating ends of lines of weakness 12 and the top edges of bag elements 10, the deepness of this out being generally denoted by reference letter X in FIG. 1. Trimming at this point enables the filled group to be separated more easily from the chain. Also, as can be appreciated, the material residing in the area denoted by X provides a secure connection between bags 10 prior to their controlled separation at module 50. The intact" material in region X thus compliments the objective of preventing a premature separation of the bags through the initial infeed of the bags into apparatus 46, and thereafter until the bags are filled and delivered to the separating module 50.
lnany event, once separated, the bags occupying the group C position, this position being indicated in dotted lines in H6. 3, are continuously moved forward and transferred into vacuum chamber 94. The flap portions 32 and 34 of bags 10 are concurrently transferred from gripping belts 72 and 74 to gripping belts 90 and 92. Upper half 98 is then lowered from the raised or open position, and engages lower half 96 to form a substantially hermetically tight enclosure about the group of filled bags contained therewithin, the bags in this position being designated as group C. As may be appreciated, flap portions 32 and 34 and adjacent regions of bags 10 are firmly held in chamber 94 in a substantially wrinkle-free extended posture between gripping belts 90 and 92 and the edges comprising gasket 116 and 1 18 of the chamber (see FIG.
Air is then evacuated through suitable tubing means whereby air internally within the bags is drawn out through apertures 36, and along edge openings 134, thereby creating a vacuum or partial vacuum within the bags. Responsive to evacuation, the upper bag wall such as wall 26, tends to lift due to pressure differences, assuming a configuration generally as is shown in dotted lines in FIG. 5. The extent of such movement or lifting is controlled by restraining bar 126 to a suficient extent to prevent wall 26 from contacting and sticking to the heated upper sealing bar 122.
Subsequently, once the desired degree of evacuation is achieved, dual air cylinder means 124 are operated to lower upper sealing bar 122 against the sealing face of lower bar 120. A closure seal is thereby formed which extends across the width of bags adjacent the upper terminating ends of strips 18 and 20, and at a region inwardly of apertures 36. Upper bar 122 is subsequently retracted by reversely operating air cylinder means 124, and chamber 94 opened to repeat the vacuumizing cycle. If desired the bags occupying the group C' position can then be fed through suitable fast feed-ofi means or the like (not shown) for automatic separation into individual packages; or alternately, can be manually separated, or packed and shipped as a group of connected packages.
While the apparatus of the present invention has been particularly described in regard to filling, vacuumizing and sealing bags where the latter are positioned horizontally, such apparatus with only minor modifications can operate at positions inclined with the horizontal or even vertically if desired. In any such positions, the principal advantages of apparatus 46 can be realized. That is, through all phases of filling, sealing, and vacuumizing, the bag tops or flap portions 32 and 34 can be maintained under positive control. Moreover, at the vacuumizing module 52, the flap portion of the bags are firmly held in an extended wrinkle-free posture during vacuumization. Thus, the tendency of the bags to wrinkle in the closure seal area is greatly minimized. By virtue of such advantages therefore maximum reliability is obtained in affecting a substantially wrinkle-free, air-tight seal as is necessary to preserve a vacuum tight environment within the bag. Moreover, the position of apertures 36 and edge opening 134 permits the vacuum to be quickly and conveniently drawn without need to insert a vacuum nozzle or the like into the bag as is oftentimes conventional.
In addition, bag elements 10 can be customized to various evacuating conditions by controlling the size of apertures 36. Most optimally therefore apertures 36 comprise port means defining an area of opening which can be varied in size, and are more desirable than slits, for example, the latter having theoretically zero width and therefore zero area of opening. Apertures placed such as at mid-region portions of the flaps 32 and 34 can alternately or additionally be employed where found advantageous such as for reasons of reducing the overall evacuation cycle time.
While certain representative embodiments and details have been shown for the purpose of illustrating the invention, it will be apparent to those skilled in the art that various changes and modifications can be made therein without departing from the spirit and scope of the invention.
1. The method of filling and evacuating a bag of a type including freely spreadable flap portions defining therebetween a fill opening, the fill opening communicating with an enclosure for receiving product fill, said method comprising the steps of: spreading said flap portions to place a product fill in the enclosure through said fill opening, thereafter holding said flap portions in an extended substantially face to face contiguous relationship by gripping the flap portions at a region spaced from said enclosure, whereby edge openings communicating with said enclosure exist in a region between the point said flap portions are gripped, evacuating said bag through an aperture formed in at least one of said flap portions, and thereafter closing said bag by forming a closure seal positioned at a region inwardly of said edge openings and said aperture.
2. The method of filling and simultaneously evacuating a plurality of bags, each of a type including freely spreadable flap portions defining therebetween a fill opening, the fill opening communicating vu'th an enclosure for receiving product fill, said method comprising the steps of: spreading said flap portions to place a product fill in the enclosure through said fill opening, thereafter holding said flap portions in an extended substantially face to face contiguous relationship by gripping the flap portions at a region spaced from said enclosure, whereby edge openings communicating with said enclosure exist in a region between the point said flap portions are gripped and said enclosure, creating a vacuum environment for simultaneously evacuating a group of at least two of said bags connected to each other through apertures formed in said flap portions, said flap portions being continuous along an edge of said group, and thereafter closing said bag by forming a closure seal positioned at a region inwardly of said edge openings and said apertures to hermetically seal the vacuum environment within said enclosure.
3. The method of successively filling and evacuating bags of a type connected together as a series of continuous bag elements, and defining along a continuous edge thereof opposed flap portions, fill openings being defined successively between said flap portions and communicating with successive enclosures for receiving product fill, said method comprising the steps of: plowing open said flap portions and successively filling said enclosures by inserting a product through the fill openings defined between the slowed open flap portions, gripping said flap portions to hold the flap portions in an extended position, said gripping force being applied to said flap portions at a region spaced from said enclosure, evacuating air from said enclosures by drawing air out through a passageway communicating with said enclosures, said passageway being defined between said flap portions in the area intermediate said gripping means and said enclosure, and thereafter closing said bag elements by forming a closure seal across said enclosure at a region inwardly of said flap portions to seal the air evacuated environment within said bags.
4. The method of claim 3 including the stop of parting said series of bag elements into groups, and successively evacuating the air immediately surrounding said groups to evacuate said bags.
5. The method of claim 4 wherein said parting step comprises breaking said bag elements apart from each other along preformed lines of weakness defined between said groups.
6. The method of claim 5 wherein said preformed lines of weakness terminate short of said continuous edge, said method comprising the step after filling of trimming the region of said bags located between said continuous edge and approximately the adjacent terminating ends of said lines of weakness.
7. The method of claim 3 including the step of evacuating said bags through apertures made in at least one of said flap portions.
8. The method of filling and evacuating preformed bags of a type connected together in series, the series of bags defining along a continuous edge thereof opposed freely spreadable flap portions, successive fill openings being defined between said flap portions, and communicating with successive enclosures, said method comprising the steps of: spreading apart said fill openings and inserting a product fill therebetween into said enclosures, respectively, successively parting groups comprising at least one filled bag from said series of bags, gripping the flap portions of said parted group between opposed belts and delivering the enclosure of said parted group into a vacuum chamber including opposed mateable halves, leaving a region of said flap portions spaced from said enclosures interposed between opposed edges of said halves; closing said halves to form a substantially hermetically tight chamber about said parted group with said region of said flap portions being held firmly in an extended fashion-between said edges, evacuating said chamber to evacuate air from said parted group, forming a closure seal located at a region inwardly of said flap portions to hermetically seal the evacuated environment within said enclosure of said parted group.
9. The method of claim 8 wherein said parting step comprising breaking about said group along a preformed line of weakness.
10. The method of claim 8 wherein said line of weak- I ness terminates at a region spaced from said continuous edge, said breaking apart step being accompanied by trimming from said bags the region of material located between said continuous edge and approximately the