U.S. patent number 3,688,463 [Application Number 05/055,141] was granted by the patent office on 1972-09-05 for vacuum packaging system.
This patent grant is currently assigned to The Dow Chemical Company, Midland, MI. Invention is credited to Oliver R. Titchenal.
United States Patent |
3,688,463 |
|
September 5, 1972 |
VACUUM PACKAGING SYSTEM
Abstract
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.
Inventors: |
Oliver R. Titchenal (Berea,
OH) |
Assignee: |
The Dow Chemical Company, Midland,
MI (N/A)
|
Family
ID: |
21995899 |
Appl.
No.: |
05/055,141 |
Filed: |
July 15, 1970 |
Current U.S.
Class: |
53/434; 53/469;
53/459; 53/481 |
Current CPC
Class: |
B65B
31/021 (20130101) |
Current International
Class: |
B65B
31/02 (20060101); B65b 031/02 () |
Field of
Search: |
;53/22R,22A,22B,79,86,112A,112B |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Travis S. McGehee
Attorney, Agent or Firm: Gustalo Nunez
Parent Case Text
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.
Claims
I claim:
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 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 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 weakness 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
terminating end of said line of weakness.
11. The method of claim 8 wherein said evacuating step includes the
step of evacuating said group through an aperture formed in at
least one of said flap portions.
Description
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 difficult 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.
Difficulties 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.
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.
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 18 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 12
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 "soft"
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 58
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 affect 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 10 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 U.S. 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 12; namely, every third
line of weakness for groups consisting of three bags. The separated
group is then moved forward on conveyor belt 70 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 80 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 cut 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.
In any event, once separated, the bags occupying the group C
position, this position being indicated in dotted lines in FIG. 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 118 of the chamber (see FIG.
5).
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 sufficient 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 10 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-off 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.
* * * * *