TREA

Method for manufacturing flexible packages having slide closures

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Information

  • Patent Grant
  • 6769229
  • Patent Number
    6,769,229
  • Date Filed
    Thursday, August 30, 2001
    22 years ago
  • Date Issued
    Tuesday, August 3, 2004
    19 years ago
Information
Abstract
Vertical form fill seal apparatus for making flexible packages with slider fastener closures is provided. A fastener track is applied in-line with a plastic web and is bonded thereto at the same time that a peel seal is formed. All package components are brought together at the point of fill. Prior to assembly at the fill station a series of spaced-apart stop members are formed along the fastener tracks.
Description




BACKGROUND OF THE INVENTION




1. Field of the Invention




The present invention pertains to the manufacture of flexible packages, such as plastic bags, and in particular to packages having fastener closures employing sliders.




2. Description of the Related Art




With the recent emphasis in providing consumers with bulk quantities of various commodities, such as food products, reclosable packages have become increasingly popular. One of the most popular means of providing reclosability is to employ zippers of various types, particularly zippers which are compatible with flexible packages of plastic film construction. Manufacturers of food products and other commodities are concerned with filling the contents of a flexible package as quickly and economically as possible. It is important that the opening provided by the fastener be made as large as practically possible. Consumers or other end users also prefer large sized openings for easy extraction of products from the package interior. Even with large openings, however, products within the package may interfere with fastener operation when product poured or otherwise dispensed from the package becomes entrained in the fastener components.




Other improvements to flexible reclosable packages are being sought. For example, when handling products comprised of numerous small pieces, such as shredded cheese or cereal, for example, it is generally desirable to have the package formed into a pouch which is open at one end, or along one side, so as to allow product to be poured or shaken through the reclosable opening. It is desirable that the product be allowed to freely flow past the reclosable opening. Preferably, the path taken by the product within the package should be made as smooth as possible.




Although improvements have been made in the art of plastic welding and joining, manufacturers of consumer products employing high speed production techniques are continually seeking improved package forming methods and equipment.




SUMMARY OF THE INVENTION




It is an object of the invention to provide apparatus for manufacturing improved flexible packages.




Another object of the invention is to provide apparatus for making reclosable packages having fastener sliders which are protected as the package contents are poured out or otherwise extracted.




A further object of the invention is to provide apparatus for making a reclosable plastic package having a slider fastener with improved containment of the slider in a manner which also optimizes the size of the bag opening.




A further object of the invention is to provide apparatus for making a plastic bag having a slider fastener with an improved end—“crush” stop of the fastener tracks.




These and other objects of the invention are attained in a vertical form-fill seal machine for the in-line manufacturing of food packages having zipper slider closures. The machine includes a supply of web material extending in a machine direction, including a chain or serial succession of food package portions extending in the machine direction. A supply of fastener track with male and female zipper parts is provided. The collar member receiving web material. The web drive transports web material over collar in the machine direction, folding the web into overlying side-by-side portions, one against the other to form a pair of overlying package walls. The supply of slider members are mateable with the fastener track for movement along the fastener track in opposite directions to open and close the fastener track. The slider installation member engages slider members with the fastener track. A pair of zipper seal bars seals to the package wall a portion of the fastener track extends in the machine direction. A pair of peel seal bars extends in the machine direction for forming a peel seal coupled between the package walls. A pair of spaced-apart side seal bars extends at an angle to set machine direction and seal portions of the package walls together to form respective side seals of the food package. The side seal bars and peel seal bar cooperate with the second seal bar to form a closed package.




It has been found difficult in a practical commercial environment to reliably employ conduction heat sealing techniques to form the slider stop. It is preferred that the stop be formed using ultrasonic sealing techniques, as these afford greater control over dimension and shape. This is important when the frontal surface area of the stop (and optionally, the overall mass) is reduced to the greatest extent possible.











BRIEF DESCRIPTION OF THE DRAWINGS





FIG. 1

is a fragmentary front elevational view of a flexible package according to principles of the present invention;





FIG. 2

is a fragmentary cross-sectional view taken along the line


2


—


2


of

FIG. 1

;





FIG. 3

is a fragmentary end view indicated by line


3


—


3


of

FIG. 1

;





FIG. 4

is fragmentary front elevational view showing construction of the flexible package;





FIG. 5

is a top plan view of the slider member;





FIG. 6

is a front elevational view thereof;





FIG. 7

is an elevational view from one end thereof;





FIG. 8

is an elevational view from the other end thereof;





FIG. 9

is an end view of a fastener track sub-assembly;





FIG. 10

is a cross-sectional view, in schematic form, taken along the line


10


—


10


of

FIG. 1

with the slider moved to the left;





FIG. 10



a


is a fragmentary view, of

FIG. 10

shown on an enlarged scale;





FIGS. 10



b


and


10




c


show alternative seal constructions;





FIG. 11

is a fragmentary front elevational view showing contents being poured from the flexible package;





FIG. 12

is a fragmentary front elevational view showing contents of a prior art package;





FIG. 13

is a fragmentary front elevational view of another flexible package according to principles of the present invention;





FIG. 14

is a front elevational view of another flexible package according to principles of the present invention;





FIG. 15

is a fragmentary elevational view of a shrouded flexible package constructed according to principles of the present invention;





FIG. 16

is a fragmentary cross-sectional view taken along line


16


—


16


of

FIG. 15

;





FIG. 17

is a fragmentary end view of the package of

FIG. 15

;





FIG. 18

is a fragmentary elevational view of a further embodiment of a flexible package constructed according to principles of the present invention;





FIG. 19

is a fragmentary elevational view of another embodiment of a shrouded flexible package;





FIG. 20

is a cross-sectional view taken along the line


20


—


20


of

FIG. 15

;





FIG. 21

is a cross-sectional view similar to that of

FIG. 20

, shown with the schematic depiction of tooling to form the flexible package;





FIG. 22

is a fragmentary elevational view of a further embodiment of a shrouded flexible package;





FIG. 23

is a fragmentary elevational view of an additional embodiment of a shrouded flexible package;





FIG. 24

is a cross-sectional view similar to that of

FIG. 20

but showing an alternative shroud construction;





FIG. 25

is a fragmentary elevational view of a further embodiment of a shrouded flexible package;





FIG. 26

is a perspective view of manufacturing apparatus according to principles of the present invention;





FIG. 27

is a front elevational view thereof;





FIG. 28

is an elevational view from the left side thereof;





FIGS. 29



a


-


29




b


show operations performed on the plastic web;





FIG. 30

is a fragmentary perspective view thereof;





FIG. 31

is a fragmentary perspective view of a forming collar used in carrying out the present invention;





FIGS. 32-36

show the arrangement of

FIG. 30

undergoing a sequence of operational steps;





FIGS. 37



a


,


37




b


together show operation of the vertical seal bars in greater detail;





FIG. 38

is a cross-sectional view taken along lines


38


—


38


of

FIG. 37



a;







FIG. 39

is a cross-sectional view taken along lines


39


—


39


of

FIG. 37



a;







FIG. 40



a


is a fragmentary cross-sectional view taken along the line


40




a


—


40




a


of

FIG. 30

;





FIG. 40



b


is a fragmentary cross-sectional view similar to that of

FIG. 40



a


but showing a later sequence of operation;





FIG. 40



c


is a cross-sectional view of a slider member;





FIG. 41

is a fragmentary perspective view of a partially formed bag being prepared to receive a slide fastener;





FIG. 42

is a fragmentary cross-sectional view taken along the line


42


—


42


of

FIG. 41

;





FIG. 43

is a fragmentary cross-sectional view taken along the line


43


—


43


of

FIG. 44

;





FIG. 44

shows a slider being fitted to a partially formed bag;





FIG. 45

is a fragmentary perspective view of a slider insertion station;





FIG. 46

is a fragmentary exploded perspective views of an ultrasonic horn and anvil assembly according to principles of the present invention;





FIG. 47

is a fragmentary exploded perspective view of an anvil assembly with fastener tracks;





FIG. 48

is a cross-section view taken along the line


48


—


48


of

FIG. 47

;





FIG. 49

is a cross-sectional view taken along the line


49


—


49


of

FIG. 47

;





FIG. 50

is a front elevational view of the sealing horn of

FIG. 46

;





FIG. 51

is a cross-sectional view taken along the line


51


—


51


of

FIG. 50

;





FIG. 52

is a fragmentary perspective view of a prior art sealing horn;





FIG. 53

is a fragmentary cross-sectional view taken along the line


53


—


53


of

FIG. 46

;





FIG. 54

is a fragmentary cross-sectional view similar to that of

FIG. 53

but showing the sealing horn in a sealing operation;





FIG. 55

is a fragmentary elevational view of an upper corner of a flexible package according to principles of the present invention;





FIG. 56

is a cross-sectional view taken along the line


56


—


56


of

FIG. 55

;





FIG. 57

is a cross-sectional view taken along the line


57


—


57


of

FIG. 55

;





FIG. 58

is a cross-sectional view taken along the line


58


—


58


of

FIG. 55

;





FIG. 59

is a cross-sectional view similar to that of

FIG. 54

but showing the ultrasonic horn being retracted at the end of a sealing operation;





FIG. 60

is an enlarged fragmentary view of the upper portion of

FIG. 15

, shown in elevation;





FIG. 61

is a cross-sectional view taken along the line


61


—


61


of

FIG. 60

;





FIG. 62

is a cross-sectional view taken along the line


62


—


62


of

FIG. 60

;





FIG. 63

is a fragmentary cross-sectional view taken along the line


63


—


63


of

FIG. 60

;





FIG. 64

is a cross-sectional view taken along the line


64


—


64


of

FIG. 60

;





FIG. 65

is an enlarged perspective view of the synchronizing assembly of

FIG. 15

;





FIGS. 66 and 67

show elevational views of horizontal sealing bars shown above;





FIG. 68

is a fragmentary perspective view of the sealing stations;





FIG. 69

is a side elevational view of the sealing station of

FIG. 68

;





FIG. 70

is a perspective view of a side seal bar;





FIGS. 71 and 72

are fragmentary perspective views of a peal seal sealing bar;





FIG. 73

is a perspective view of a shrouded flexible package according to principles of the present invention; and





FIG. 74

is a perspective view similar to that of

FIG. 73

showing the flexible package partly opened.











DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS




Referring now to the drawings and initially to

FIGS. 1-8

, an improved flexible package is generally indicated at


10


. The terms “package” and “bag,” are used interchangeably and are not intended to refer to any relative size of the finished item.




Flexible package


10


preferably comprises a plastic bag having front and back panels


12


,


14


joined together at the left end by a side seal


20


and at the right end by a side seal


22


. Side seal


20


is preferably of conventional conduction heat-sealed construction, having a generally constant width throughout. If desired, side seal


20


can be employed on both sides of the flexible package. Panels


12


,


14


are further joined together at their bottom ends by a bottom seal


24


(see

FIG. 10

) extending between side seals


20


,


22


, as is known in the art. Alternatively, the bottom seal can be replaced by a fold line with panels


12


,


14


being formed from a continuous sheet of plastic material.




The upper end of flexible package


10


features a reclosable opening including a slide fastener arrangement with fastener tracks


26


,


28


and a slider


30


, all preferably of polyolefin material. The slider


30


is slidable along the fastener tracks, causing the fastener tracks to interlock or mate (as shown in

FIG. 2

) for closure of the flexible package and to unmate or separate to open the flexible package for access to contents in the package interior. As will be seen herein, features associated with the fastener slider arrangement allow an unprecedented enlarged opening of the flexible package. The enlarged package opening made possible by the present invention benefits manufacturers filling the package, as well as consumers dispensing product from the interior of the flexible package. In the preferred embodiment shown, the fastener tracks are also referred to as “zipper” tracks.




The flexible package according to principles of the present invention has found immediate commercial acceptance for use with food products, including perishable food products, such as cheese. Accordingly, it is generally preferred that the flexible package includes a hermetic seal


36


in the form of a peelable seal as taught in commonly assigned U.S. Pat. Nos. 5,014,856; 5,107,658 and 5,050,736, the disclosures of which are incorporated by reference as if fully set forth herein.




As mentioned above, flexible package


10


preferably comprises a bag having panels


12


,


14


formed from plastic sheet material. The sheet material can be of a single material type, such as polyolefin materials including polyethylene and polypropylene, but preferably comprises a laminate assembly of several different material types, as is known in the art to provide a barrier to moisture as well as certain gases, such as oxygen or inert fillers of the types used with food products. Other types of laminate films, such as those known in the art to preserve food freshness, may be employed. Where the contents of the flexible package are not perishable or where other considerations may dictate, the panels


12


,


14


can be constructed without regard to gas or vapor barrier properties.

FIGS. 2 and 3

indicate that it is generally preferred that the fastener tracks be joined to web-like flanges which, in turn, are joined to panels


12


,


14


as will be described below with reference to FIG.


10


.




Referring now to

FIGS. 5-8

, fastener slider


30


has a top wall


44


, a shorter side wall


46


and a longer side wall


48


, cooperating to define an internal cavity


50


for receiving the fastener tracks


26


,


28


. As can be seen by comparing the end views of

FIGS. 7 and 8

, a first end


54


of the slider defines a cavity which is generally rectangular. The opposed end


56


(shown in

FIG. 8

) defines a cavity which is generally arrowhead or A-shaped, as indicated by reference numeral


50




b


, conforming to the outline of the interlocked fastener tracks shown in FIG.


2


. When the slider


30


of

FIG. 1

is moved to the right, end


56


is at the leading end of the slider and the fastener tracks


26


,


28


are unlocked, thus opening the flexible package


10


. Conversely, as slider


30


of

FIG. 1

is moved to the left, end


54


(shown in

FIG. 7

) is made the leading end, and fastener tracks


26


,


28


are interlocked in the manner indicated in

FIG. 2

, to close the flexible package.




Referring again to

FIGS. 2

,


7


and


8


, a number of features cooperate to maintain slider


30


captive on fastener tracks


26


,


28


. As can be seen for example in

FIG. 8

, a pair of upwardly facing stepped portions


62


are formed on either side of the slider cavity. Inwardly extending protrusions


64


are located at the other end of the slider. Protrusions


64


and stepped portions


62


engage the bottoms


26




a


and


28




a


(see

FIG. 2

) of fastener tracks


26


,


28


, as can be seen for example in FIG.


10


. The engagement of the stepped portions


62


and the protrusions


64


with the bottoms of the fastener tracks prevents the slider from being upwardly dislocated from the fastener tracks.




Referring to

FIGS. 1

,


3


and


13


, the ends of the fastener tracks are deformed or “crushed” to form stops


68


. Preferably, stops


68


are formed by the application of ultrasonically generated heat and pressure to the ends of fastener tracks


26


,


28


. It has been found that the use of present day conduction heat sealing techniques does not provide the control needed to attain the intricate, close tolerance design of stop members according to principles of the present invention. Further, it has been found that the use of present day conduction heat sealing techniques immediately adjacent previously formed stop members tends to distort the stop members, oftentimes to an extent rendering the stop members unacceptable from a quality control standpoint. As will be seen herein, stops


68


are configured for maximum efficiency, having the smallest front elevational surface area (i.e., the surface area visible in

FIGS. 1 and 13

, for example), which is adequate for containing slider


30


on the fastener tracks.




Referring to

FIG. 3

, the sides of the fastener tracks are softened and compressed at stop faces or sides


72


so as to impart a pre-selected width w and an upwelling displacement u above the upper surfaces


26




b


,


28




b


of fastener tracks


26


,


28


(see FIG.


2


). The material displaced above the upper surface of the fastener tracks interferes with the top wall


44


and ends of slider


30


to limit its sideways travel.




With reference to

FIG. 3

, the slider stop


68


(that is, the deformed portion of fastener tracks


26


,


28


) is carefully configured so as to avoid deformation of the bottom surfaces


26




a


,


28




a


of the fastener tracks. With reference to

FIG. 1

, the lower ends of the fastener tracks extend undeformed, substantially to the side edges


16


,


18


of the flexible package


10


.

FIG. 1

shows slider


30


“parked” at a fully opened position, with end


56


contacting the stop


68


located at the right hand end


22


of the flexible package. Stop members


68


and the undisturbed bottom surfaces


26




a


,


28




a


of the fastener tracks in the area of stop members


68


cooperate to captivate slider


30


on the fastener tracks, preventing its unintentional removal from flexible package


10


.




It is preferred that the bottom edges


26




a


,


28




a


remain undeformed also for that portion extending beyond slider


30


, and underneath at least a portion of the right hand stop


68


. With reference to

FIG. 3

, a gap q is formed between the bottom edges of the fastener tracks and the top portion


81


of side seal


22


. As can be clearly seen in

FIG. 3

, the stop


68


, formed by ultrasonic techniques, is separated by a substantial distance from the side seal, which is typically formed using conduction heat seal techniques found to be incompatible with the precise, high resolution ultrasonic techniques used to form stop


68


. A second stop


68


formed at the left hand end


16


of flexible package


19


is constructed in a similar fashion and extends beyond the end


54


of slider


30


when the slider is moved fully to the left, closing the upper end of the flexible package. As will be explained in greater detail herein, separation of the “crush” operation performed on the fastener tracks to form stops


68


from the conduction heat sealing operation to form the enlarged side seals, allows stops


68


to take on a reduced size, effectively extending the size of the package opening, without sacrificing ability of the stops to effectively retain slider


30


on the fastener tracks.




Referring to

FIGS. 1 and 4

, side seal


22


includes an upper enlarged or tapered portion


80


having a width substantially greater than the lower end of side seal


22


, sufficient to underlie the substantial entirety of slider


30


when the slider is fully moved to the “parked” position as shown in FIG.


1


. The width of the enlarged, tapered portion


80


ranges between 200% and 400% (or more for very narrow side seals, e.g., 2 mm or less) of the width s of side seal


22


and most preferably ranges between 250% and 300% of the side seal width s.




The enlarged, tapered end


80


of side seal


22


has a S-shaped or double re-entrant bend contour


84


which partly defines the package interior. With reference to

FIG. 11

, the curved edge


84


of the enlarged side seal portion


80


provides a smooth transition at the corner of the package opening, preventing product entrapment within the flexible package. As those skilled in the art will appreciate, the smooth transition at the opening corner is especially beneficial for flexible packages, where shaking techniques otherwise suitable for rigid packages, are rendered largely ineffective by flexible panels


12


,


14


and especially panels of very thin, unsupported material which are likely to collapse in use.




The smooth transition provided by curved edge


84


also deflects or guides product


86


away from slider


30


as product is poured or otherwise removed from flexible package


10


. This prevents contamination of mating surfaces of the slider and the fastener tracks, which would otherwise deteriorate the ability of slider


30


to move freely, performing interlocking and unlocking of the fastener tracks. As indicated in

FIG. 12

, in prior art arrangements product


86


is allowed to freely contact the bottom end of slider


30


, a condition which is avoided by flexible packages according to principles of the present invention.




Preferably, fastener tracks


26


,


28


are “crushed” to form stop member


68


, using conventional ultrasonic heating equipment which allows for a highly accurate shaping of the stop member as well as withdrawal of the deformation area away from the bottom surfaces


26




a


,


28




a


as shown, for example, in FIG.


3


. As can be seen for example in

FIG. 1

, the width of stop member


68


is considerably less than the enlarged tapered portion


80


of side seal


22


, and preferably is of a smaller width than that of the narrower major portion of side seal


22


. With reference to

FIG. 1

, the width d of stop member


68


is less than the width s of side seal


22


. Preferably, stop member width d ranges between 50% and 200% of the width s of side seal


22


. Preferably, the width w of the stop member


68


(i.e., the “crush” dimension) ranges between 25% and 80% of the width z of the fastener tracks, as illustrated in FIG.


3


. The amount of upward displacement or upwelling u is approximately at least as great as the thickness of upper wall


44


. It should be kept in mind that the total mass of the stop must be sufficient to hold the slider captive.




The stop member


68


, in addition to having a reduced width d in front elevational view and a small width w in end view (see FIG.


3


), has a sufficiently smaller mass and frontal surface area than stops employed in the prior art. This construction allows the slider


30


to be moved to an extreme position immediately adjacent the edge


22


of flexible package


10


, thus maximizing the package opening, allowing for easier removal of the package contents. This reduced size of stop


68


also contributes to the precision of the ultrasonic heating and formation of the stop member, needed to attain required precise dimensions. Further, from a manufacturing standpoint, the dwell time to melt and shape the stop


68


is substantially reduced, contributing to the overall efficiency for the package manufacturer.




Prior art stop members have been formed by “crushing” the entire fastener profile, including the bottom surfaces


26




a


,


28




a


. In addition, even if ultrasonic techniques are employed for the stop member, prior art side seals (formed using conduction heat seal techniques and much larger, oftentimes three to four times larger than side seals according to the present invention) were typically overlaid with the stop, contributing to a substantial distortion of the stop structure. Even if the prior art side seals were made to stop short of the fastener tracks, the relatively high level of conduction heating in the immediate proximity of the stop have been found to cause a distortion of the stop, degrading control over its size and shape. These disadvantages are avoided with practice of the present invention, where the small, compact size of the stop is employed, and the gap g is formed between undeformed fastener bottom surfaces


26




a


,


28




a


and the enlarged seal portion


80


.




Turning now to

FIGS. 4

,


9


and


10


, and initially to

FIG. 9

, the fastener tracks are preferably formed from a sub-assembly generally indicated at


70


in which the fastener tracks


26


,


28


are provided with corresponding fastener flanges


72


,


74


. The fastener flanges


72


,


74


are coextensive with the fastener tracks


26


,


28


and take the form of a plastic web to be heat sealed to the panels


12


,


14


. As can be seen in

FIG. 9

, fastener flange


74


is shorter in height than fastener flange


72


, so as to accommodate the preferred hermetic seal arrangement shown in FIG.


10


.




The fastener flanges


72


,


74


are heat sealed to panels


12


,


14


. With reference to

FIGS. 4 and 10

, fastener flange


72


is welded or otherwise mechanically sealed to panel


12


at weld band


78


. As shown at the upper portion of

FIG. 10

, the upper ends of panels


12


,


14


are joined to the outer outwardly facing surfaces of fastener flanges


72


,


74


at points intermediate the fastener tracks and peelable seal


36


. Band


36


preferably comprises a hermetic peelable seal formed by the joinder of panel


14


to the inside face


72




a


of fastener flange


72


(see

FIGS. 10 and 10



a


). Panel


12


is sealed to the opposite outside face of the fastener flange as schematically indicated in FIG.


10


. In

FIG. 10



a


the components of the peelable seal


36


are shown, with film


12


, which plays no part in the preferred peelable seal, being shown in phantom.




Variations of the peelable seal are also contemplated by the present invention. For example, in

FIG. 10



b


, the flanges


72


,


74


of the fastener arrangement are joined with a peelable seal. The upper ends of these flanges are heat sealed to panels


12


,


14


as shown. In

FIG. 10



c


a further alternative is shown with the peelable seal


36


being formed at the joinder of lower portions of panels


12


,


14


. the upper portions of panels


12


,


14


are heat sealed to fastener flanges


72


,


74


.




As will now be appreciated, the enlarged, tapered end portions


80


of side seal


22


cooperate with other features of flexible package


10


to provide a number of important advantages. More specifically, the enlarged tapered end portions


80


provide a smooth transition of the interior of flexible package


10


preventing product entrapment in the slider and fastener track surfaces when product is poured or otherwise dispensed. In addition, the enlarged tapered portion


80


helps to secure slider


30


about tracks


26


,


28


by maintaining a clearance from bottom surfaces


26




a


,


28




a


of the fastener tracks. Further, the enlarged tapered portions


80


of side seals


22


strengthen and rigidify edge portions of panels


12


,


14


in the immediate area of the parked position of slide


30


.




Often, the greatest amount of force applied by the user to slider


30


occurs at the closing of the slider, when the fastener tracks are unlocked or separated from one another. When the slider


30


is in the middle of its travel along the fastener tracks, the user is provided with a sensation of the proper direction of slider movement. However, when the slider


30


is in the parked position, and especially in the “parked open” position shown in

FIG. 1

, the user's initial application of force may be misdirected. The enlarged tapered portion


80


provides added stiffness and rigidity to the flexible package at the initial point where pressure is applied to the slider, thus further contributing to the assurance that secure engagement will be maintained between slider


30


and the tracks


26


,


28


.




With reference to

FIG. 4

, a consumer desiring to close the flexible package will grasp the enlarged side seal portion


80


, pulling in the direction of arrow


81


while pulling or pushing slider


30


in the direction of arrow


31


. The added stiffness and rigidity offered by enlarged side seal portion


80


is provided at a point of optimal effectiveness to react in an appropriate manner to forces applied to slider


30


and to overcome any resistance of the tracks


24


,


26


to resume a mating, interlocked condition as the fastener tracks are interlocked. Those skilled in the art will appreciate that the “rolling resistance” or dynamic resistance to movement of slider


30


is oftentimes lower than the initial static resistance, opposing movement of the slider away from the fully opened parked position shown, for example, in FIG.


4


.




The added stiffness and rigidity imparted to the flexible package


10


and especially panels


12


,


14


by enlarged side seal portion


80


results in other advantages when lightweight panels


12


,


14


are employed. For example, panels of the single polyolefin type where no laminate film (such as PET or NYLON) is used to stiffen and support the support panel, have oftentimes excluded the use of sliding zippers, since minimum stiffness and rigidity needed to operate a fastener slider was not available. However, with enlarged side seal portions according to principles of the present invention, adequate stiffness is provided, even for lightweight, so-called “single” films.




As indicated in

FIG. 10

, flanges


72


,


74


are joined to respective panels


12


,


14


, preferably at their lower ends, so as to prevent product from entering between flange


72


and panel


12


, as well as between flange


74


and panel


14


. In certain applications this may not be a critical requirement. In

FIG. 10

, the upper portion of panel


12


is shown for illustrative purposes as spaced from the lower end of flange


72


. In practice, it is generally preferred that this spacing be eliminated, with panel


12


being in intimate contact with flange


72


. Similarly, any gap between panel


14


and the lower end of fastener flange


74


is preferably eliminated. Although it is most preferred that the peelable seal be formed by joining panel


14


to fastener flange


72


, the peelable seal, preferably a hermetic seal, can be formed between the fastener flanges


72


,


74


or directly between the panels


12


,


14


, although these alternative constructions are less preferred than the arrangement shown in FIG.


10


.




Turning now to

FIG. 13

, flexible package


10


is shown constructed with the panels


12


,


14


, side seal


22


, upper enlarged side seal portion


80


and fastener tracks


26


,


28


, as described above. The fastener tracks


26


,


28


are preferably joined to flanges


72


,


74


(not visible in FIG.


13


).

FIG. 13

schematically illustrates commercial fabrication of flexible package


10


. As will be appreciated by those skilled in the art, practical commercial assembly requires recognition of tolerances of the equipment and materials used to construct a viable commercial product. For example, tracks


26


,


28


are ultimately mechanically coupled to panels


12


,


14


using conduction heat seal tooling. A gap


110


shown in

FIG. 13

represents the tolerance range or margin of error for tool alignment used to secure the fastener tracks


26


,


28


. As mentioned, it is preferred that the upper end of enlarged side seal portion


80


be spaced below the lower ends of the fastener tracks, such as the lower end


26




a


of fastener track


26


visible in FIG.


13


. Further, it is preferred that the gap g continue beyond the end


56


of slider


30


.




A gap


116


represents a tolerance range or margin of error for the desired positioning of the upper end of enlarged side seal portion


80


, to provide clearance for the bottom edge of slider


30


. As illustrated in

FIG. 13

, the upper end of enlarged side seal portion


80


falls at an outermost limit of its tolerance range. Preferably, the upper end of enlarged side seal portion


80


is within the gap


116


, rather than to one end thereof. The gap


116


also accounts for any cant or angular mis-positioning or mis-alignment where the upper end of side seal


80


may be angled slightly from a position parallel to the fastener tracks, as may be encountered in a practical commercial environment.




A band


120


shown in

FIG. 13

represents a conduction heat seal of the fastener flange to the panels


12


or


14


. This conduction heat seal


120


provides the principal mechanical attachment of the fastener track assembly to the package panels. Band


36


is the peelable seal, preferably a hermetic seal, between panel


14


and fastener flange


72


. A gap


124


represents the desired production spacing between production seal


120


and peelable seal


36


. The remaining band


128


represents the production tolerance range or margin of error for positioning of peelable seal


36


with respect to the package panels.




In one commercial embodiment, flexible package


10


comprises a plastic bag having a width of approximately 6.5 inches from side edge to side edge and a total overall height of approximately 10.75 inches. The fastener tracks


26


,


28


have a height of approximately 4 millimeters, with gaps


110


,


116


each having a height of 2 millimeters. As shown in the upper right hand corner of

FIG. 13

, stop


68


projects a distance u above the top edge of the fastener tracks. In

FIG. 13

, only the top edge


26




b


is visible. With reference to

FIG. 10

, the upper ends of panels


12


,


14


are preferably spaced a distance p from the bottom edges of the fastener tracks, ranging between 2 and 3 millimeters. The conduction heat seal


120


and the peelable seal


36


each have a height of 6 millimeters, and gap


124


located between the two, has a height of 2 millimeters. The desired spacing between conduction heat seal


120


and peelable seal


36


has a maximum value of 2 millimeters and a minimum value required to prevent overlap of the conduction heat seal and peelable seal. The side seal


22


has a width ranging between 3 and 8 millimeters and the stop


68


has a width (see reference character d in

FIG. 1

) ranging between 2.0 and 8.0 mm. As can be seen with reference to

FIG. 13

, the upper end of side seal


22


is spaced a substantial distance below the upper edge of the flexible package. This spacing ranges between a minimum value equal to the combined height of the fastener tracks and gap


110


, and a maximum value equal to the combined height of the fastener tracks, gap


110


and gap


116


.




Referring to

FIG. 14

, several alternative features are shown with reference to a flexible package


130


. The right hand portion of flexible package


130


is identical to flexible package


10


, described above, except for the addition of a peg hole


132


formed in the enlarged side seal portion


80


. Flexible package


130


has a left side seal


20


as described above with respect to FIG.


1


. However, in the flexible package


130


, the upper end of side seal


20


is enlarged at


138


in a manner similar to that of enlarged side seal portion


80


. An optional peg hole


140


is formed in the enlarged side seal portion


138


. Although the peg holes


132


,


140


are shown having a circular shape, virtually any shape (e.g., oval) can be used, as well. Peg holes


132


,


140


can be formed by punching before or after the side seals are fully formed, it being preferred that the upper ends of the side seals provide a complete sealing of the panels and other components of the flexible package. It will be appreciated by those skilled in the art that the holes add heat relief to the enlarged side seal portion. This helps preserve the uniformity of the tapered area and of the dimensioning of gap g, as well as the uniformity of shrinkage which helps control manufacture on a production basis. If desired, the heat sealing die can be made hollow in the region of the peg holes, even in the absence of peg hole features to attain further heat relief advantages. It may also be preferable in some instances to form the peg holes


132


,


140


as part of the formation of the side seals using, in effect, a thermal cutting or thermal punching technique. With the inclusion of two peg holes


132


,


140


, flexible package


130


can provide an improved presentation of art work or other indicia carried on the panels of the flexible package.




It is generally preferred that textual and graphic information be oriented generally perpendicular to the side edges of the flexible package. If only one peg hole is provided, the package will tend to hang rotated in a vertical plane, according to the distribution of product within the flexible package. With support given to two peg holes


132


,


140


, the flexible package is oriented in an upright position, making it easier to read the text and graphical information carried on the package. If desired, the text and graphical information printed on the rear panel can be inverted so that a consumer can “flip” the package to inspect the rear panel, without having to remove the package from the support pegs passing through peg holds


132


,


140


.




Although the package opening, fastener tracks and related features are shown at the upper end of the flexible package, the present invention is intended to cover arrangements in which the opening and related structure is provided on the side or bottom of the flexible package.




Referring now to

FIGS. 15-25

and initially to

FIG. 25

, an improved package according to principles of the present invention, is shown. Package


199


includes the features of flexible package


10


, described above and in addition includes a shroud portion


204


extending above line of weakness


208


formed in panels


12


,


14


. Line of weakness


208


can be formed using available conventional techniques, and is preferably formed, using laser scoring techniques. Preferably, line of weakness


208


extends across the width of flexible package


199


, from one side edge to the other. As shown in

FIG. 25

, line of weakness


208


extends to edge


18


, located at side seal


22


. If desired, side seal


2


can be replaced by side seal


20


.




Preferably, shroud


204


is made for easy tear-away removal in an intuitive manual operation not requiring special directions. Preferably, a notch


210


is formed in edge


18


, and is located slightly above stop


68


. An optional angled or diagonal line of weakness


212


extends from notch


210


to an opening


214


which surrounds slider


30


. Opening


214


is illustrated as a rectangle with rounded corners. Opening


214


can however take on other shapes, such as that of a circle or teardrop, for example. Opening


214


relaxes the strain in the shroud portion of the flexible package caused by relatively large-sized slide members. It is preferred that the opening


214


be formed in the web prior to joining with fastener tracks. Accordingly, careful registration of the opening


214


is needed to insure the desired finished flexible package is produced.




Preferably, slider


30


is located at a fully closed position along the fastener tracks and is surrounded by opening


214


at the closed position. In order to gain access to the package contents, a user grasps the upper edge of shroud


204


causing an initially tearing at notch


210


. Tearing continues along diagonal line


212


and enters opening


214


, continuing along opening


214


to line


208


. With continued tearing across the width of package


199


, the shroud


204


is removed, leaving a package substantially similar to the packages described above in

FIGS. 1-14

.




Referring again to

FIG. 25

, shroud


204


includes an upper fin seal


220


and a side fin seal portion


222


. Preferably, the upper fin seal


220


inside fin seal


222


are formed in separate sealing operations and are made to slightly overlap one another for package integrity and sealing of the package interior. The bottom of side fin seal


222


is terminated at or slightly above end stop


68


. It is most preferred that side fin seal


222


be terminated slightly above end stop


68


to avoid interfering with the controlled formation of the end stop which, as pointed out above, has a shape and position providing novel advantages. Notch


210


in the preferred embodiment shown in

FIG. 25

is formed at the lower end of side fin seal


222


. If desired, notch


210


could be formed in a gap between end stop


68


and a side fin seal shortened with respect to the side fin seal illustrated in FIG.


25


.




Turning now to

FIGS. 15-18

a flexible package


230


is shown. Package


230


is substantially identical to package


199


described above, except that opening


214


does not directly communicate with diagonal line


212


. Tearing of package


230


to remove shroud


204


is initiated at notch


210


and continues along diagonal line


212


to a point of intersection with line of weakness


208


. If desired, the portion of weakness line


208


designated by reference numeral


232


, line between diagonal line


212


and edge


18


can be omitted, if desired. Further, weakening line


208


and diagonal line


212


can be formed in a single operation using conventional techniques such as laser cutting. As a further alternative, diagonal line


212


can be made to curve either along its entire length, or at the point of intersection with weakening line


208


.

FIG. 15

shows a central peg hole


234


is formed in upper fin seal


220


.




Referring now to

FIG. 19

, flexible package


240


is substantially identical to flexible package


230


, except for the omission of opening


214


. Arrangement of

FIG. 19

is preferably employed where the width of slider


30


is reduced, or the shroud


204


is sufficiently flexible or has an enlarged cross section so as to completely enclose slider


30


without requiring an opening to relax tension in the material forming the shroud.




Referring now to

FIG. 20

, a cross section of flexible package


199


is shown. Preferably, shroud


204


is formed as a continuous integral extension of panels


12


,


14


, the upper free edges of which are joined together to form upper fin seal


220


.




Referring to

FIG. 21

, exemplary tooling to form the package


199


are shown. For example, a pair of upper seal bars


250


form upper fin seal


220


while a pair of intermediate seal bars


252


join panels


12


,


14


to fastener flanges


72


,


74


. Lower seal bars


254


form the peel seal


36


and weld band


78


(FIG.


20


). The bottom of package


199


, as is preferred, with the other flexible packages shown herein, is formed by a dead fold


258


.




Referring now to

FIG. 22

, a flexible package


260


is substantially identical to flexible package


230


of

FIG. 18

, except for a curved line of weakness


264


joining notch


210


with weakening line


208


.





FIG. 23

shows a flexible package


270


similar to that of flexible package


230


, except that a large or tapered side seals are provided at each side of the package. Peg holes


132


,


140


are formed in the tapered side seal portions and if desired an optionally central peg hole


234


can be formed in upper fin seal portion


220


. As with the other embodiments shown herein, it is generally preferred that the enlarged or tapered side seal portions stop short of the line of weakness


208


.





FIG. 24

is a cross-sectional view of an optional flexible package


280


substantially identical to flexible package


199


, described above, except that a shroud member


282


is separately formed from panels


12


,


14


and is joined to the upper ends of the panels by conventional welding or other joining techniques. Most preferably, shroud


282


is joined to the upper ends of panels


12


,


14


at the point of sealing with flanges


72


,


74


. The weakening line for removal of shroud of


282


can be formed either above or below the point of sealing with remainder of the flexible package.




It is generally preferred that textual and graphic information be oriented generally perpendicular to the side edges of the flexible package. If only one peg hole is provided, the package will tend to hang rotated in a vertical plane, according to the distribution of product within the flexible package. With support given to two peg holes


132


,


140


, the flexible package is oriented in an upright position, making it easier to read the text and graphical information carried on the package. If desired, the text and graphical information printed on the rear panel can be inverted so that a consumer can “flip” the package to inspect the rear panel, without having to remove the package from the support pegs passing through peg holds


132


,


140


.




Although the package opening, fastener tracks and related features are shown at the upper end of the flexible package, the improved flexible package is intended to cover arrangements in which the opening and related structure is provided on the side or bottom of the flexible package.




Turning now to FIG.


26


and following, apparatus for manufacturing improved flexible packages having slide closures will now be described. As will be seen herein, the apparatus according to principles of the present invention, generally indicated at


200


employs a vertical form fill seal arrangement with the in-line application of mated fastener tracks to a folded web. Apparatus


200


brings all of the required packaging components together, for assembly, at the point of fill.




Referring to

FIGS. 26 and 27

, apparatus


200


includes a web supply roll


204


providing a supply of web material


206


preferably comprising a conventional plastic packaging film. Referring to

FIGS. 29



a


,


29




b


web material


206


is advanced in the direction of arrow


600


. Punches


602


are schematically indicated and form the openings


214


on opposed bag panel portions


12


,


14


. In

FIG. 29



b


dotted line


606


indicates a crease or a fold line about which web


206


is folded to form a “dead fold” at the bottom of the finished bag, as explained above. Also, indicated in

FIG. 29



b


are diamond shape cutouts


610


formed by punches schematically indicated at


612


. The broken lines


614


running generally transverse of web


206


indicate severing lines which divide one bag portion from another, the bags preferably being serially formed from a common web


206


. After severing, the diamond cutouts become tear notches


210


shown for example in FIG.


25


.




A supply of mated fastener track


210


(preferably comprising fastener tracks


26


,


28


) is supplied on roll


212


. Preferably, the fastener tracks include respective mounting flanges which overly one another, and which extend along with the mated fastener tracks. As can be seen, the mounting flanges are of unequal height (with the food package viewed in an upright position) and extend from the fastener tracks different amounts. Further details concerning the construction and operation of the mated fastener tracks


210


and slider


30


of the preferred embodiment may be obtained with reference to U.S. Pat. No. 6,047,450, the disclosure of which is herein incorporated by reference. The mated fastener track


210


is fed through a roll-type accumulator


216


and passes through a series of roller guides


218


to enter a work station generally indicated at


220


for forming stops


68


in the mated fastener track and for applying slide members


30


to the fastener track. As shown in

FIG. 26

, a spaced apart series of back-to-back stops


68


are formed at work station


220


and appear downstream of the work station, being fed by drive rollers


226


, shown in FIG.


23


. In FIG.


26


and figures following which show an overall view of the machine, only the ultrasonic apparatus for forming stops is shown, the slide insertion apparatus (shown in

FIG. 45

) being omitted for illustrative purposes. It is generally preferred that the slider members be inserted downstream of roller


280


. In several of the figures, the slide members have also been omitted for illustrative purposes.




Referring now to

FIG. 28

web supply roll


204


is mounted to the rear of a cabinet assembly


224


and passes through a number of accumulator rollers (not shown) to travel in a generally upward direction indicated by arrow


225


in FIG.


30


. The web then travels over guide rollers


228


,


802


to enter the rear of a forming collar


800


. Forming collar


800


is of conventional construction, and forms web


206


about a hollow mandrel


240


to take on an initial tube-like form adjacent the upper open end


242


of the mandrel. The tube-shaped web is gradually flattened as it descends along the outside of the mandrel, to fold the web into overlying side-by-side panel portions which, when divided, become the package panels


12


,


14


.




When passing below the bottom end


244


of mandrel


240


the overlapping web portions are spaced very close to one another, being held apart by the hollow mandrel bottom. Product is passed through the mandrel to fill the flexible package as it is formed in the manner to be described herein.




Web


206


is driven across collar


800


and mandrel


240


by drive belts


248


shown for example in

FIGS. 26 and 30

. Preferably, the web and mated fastener tracks are advanced in a stepwise intermittent motion. The web material and mated fastener tracks are stopped long enough to allow seal bar station


250


to perform a number of operations on the web and mated fastener track. Seal bar station


250


includes, on each side of the folded web, a panel seal bar


254


and a peel seal bar


256


. Preferably, the vertical seal bars


254


,


256


are driven back and forth toward and away from the web by an actuator


260


, preferably of the pneumatic type. Mirror image arrangements of vertical seal bars and actuators are provided on either side of the folded web.




With reference to

FIG. 30

, web


206


has a folded crease, preferably a dead fold, which can be employed to form the bottom end


266


of the bag (

FIG. 10

) or which can be heat sealed to form a reinforced fin seal (not shown). Free edges


268


of web


206


pass between the mated pairs of seal bars, as indicated in

FIGS. 38 and 39

. As can be seen, the package forming apparatus forms a “bag chain” that is, a continuous web defining a serial succession of food package portions extending in the machine direction and having pairs of overlying package walls which include overlying free edges. The forming collar forms a dead fold in the web which extends in the machine direction, forming an opening between the overlying package walls of each food package portions which is located opposite the dead fold and which is formed by free edges of the overlying web portions.




As shown in

FIG. 30

, a mated fastener track


210


is payed out in the vertical machine direction and is aligned with the free edges


268


of a folded web. The mated fastener track is welded to the free edges of the folded web panel by fastener track or panel seal bars


254


to form a weld seal


120


shown for example in FIG.


10


. The mated fastener track is thereby joined to the web material, for common advancement therewith by drive rollers


226


(see

FIG. 35

) which operate on the combined sub-assembly. As will be seen herein, a registration adjustment is provided by idler roller


280


shown in

FIG. 18

, downstream of work station


220


. As web material is driven by drive belts


248


(

FIG. 30

) and as the joined assembly of fastener track and web material is driven by rollers


226


(see FIG.


35


), mated fastener track


210


is payed out from work station


220


, passing over guide roller


284


(see

FIG. 30

) located at the upper portion of mandrel


240


, as shown in FIG.


30


.




As shown in

FIG. 40



c


an isolation bar


288


is interposed between fastener track flanges


72


,


74


for an economical weld seal formed by panel seal bars


254


.

FIG. 40



a


, shows the vertical sealing bars prior to operation of the vertical sealing bars, while

FIG. 40



b


shows the vertical sealing bars after completion of the sealing operation. It has not been found necessary to cool isolation bar


288


although, if desired cooling can be applied in a conventional manner, with bar


288


functioning as a cooling bar. With reference to

FIGS. 60 and 64

, isolation bar


288


is mounted to the lower portion of mandrel


240


and is located in front of the mandrel in the manner shown in

FIGS. 61-63

so as to be interposed between mating seal bars


254


. When operation of the vertical seal bars is completed, the joinder of the mated fastener tracks and web panels


12


,


14


is completed to form the packaging features described in

FIG. 10

, above.




A pair of mating horizontal seals


230


are provided at station


250


, as shown in FIG.


32


. The horizontal seal bars


230


are reciprocated toward and away from the web panels by horizontal independent actuators


232


which are preferably of the pneumatic type and are preferably spaced below vertical actuators


260


. The horizontal seal bars extend in a direction generally transverse with respect to the vertically downward machine direction in which the web and fastener track material travel as they pass through apparatus


200


.




The horizontal seal bars form the side seals of the flexible package as described above with reference to

FIGS. 1-14

. With reference to

FIGS. 1 and 66

, for example, the horizontal seal bars in one configuration contain an upper portion forming the right hand seal


18


, which includes tapered end portion


80


. It is also preferred that the same horizontal seal bar includes an immediately adjacent lower portion which forms the left hand seal


16


. Thus, with a single stroke of horizontal actuator


232


, mating seal bars


230


can operate on a serial chain of bags formed from a continuous web. A right hand seal


18


of a first flexible package (located at the leading end of the traveling web) is simultaneously formed with a left hand seal


16


of an immediately preceding flexible package (i.e., at the trailing end of the package) located immediately there below in the chain of (unsevered) packages.




With progressive formation of the bag chain in the forming apparatus, a series of pouches are formed, one of the time, in preparation for a filling operation. The pouches define a hollow interior between the overlying web portions, bounded by the dead fold, the peel seal and the leading side seal (which comprises the right hand side seal of the bag shown in FIG.


1


). The remainder of the pouch (corresponding to the left-hand side seal of the bag in

FIG. 1

) is, for the time being, left open. As can be seen, the pouch opening faces an upward direction, with the opening providing a convenient point of top fill for the product. This arrangement has been found to be particularly advantageous for the packaging of shredded cheese products in a high-speed automated environment.




Located between the horizontal seal bars is a cutting blade


500


(see

FIGS. 66 and 67

) where the chain of bags is severed, dividing the trailing side seal


16


of a lower bag from the leading side seal


18


of an upper bag, thereby separating a completely formed flexible package from the monolithic chain of bags being processed by apparatus


200


. Severing of the web and mated fastener tracks is preferably carried out under tension. It is generally preferred that the web drive and drive controls associated with the web position sensor cooperate to tension the web material and mated fastener tracks while the horizontal sealing bars carry out a simultaneous cutting and side seal forming operation.




As pointed out above, it is generally preferred that the slide members be installed on the fastener tracks at an early stage of machine operation, prior to joining fastener tracks and the web forming the bag side panels. However, if desired, the slide members could be inserted after the fastener tracks are mated to the web forming the bag side panels. However, if the slider member is inserted after joining of the fastener tracks to the web forming the bag side panels, it is preferred that a separate vertical seal be applied to close the shroud, at the upper portion of the flexible package.




Referring to

FIGS. 66 and 67

, examples of horizontal seal bars are illustrated. In

FIG. 66

a horizontal seal bar


230


is used to form the flexible package shown in FIG.


1


. The upper seal bar portion


233


forms seal


22


(shown at the right hand of

FIG. 1

) while the lower seal bar portion


235


forms the side seal


20


(shown in the left hand portion of FIG.


1


). A line


231


divides upper and lower seal bar portions


233


,


235


and defines a cut line along which the chain of bags is subsequently severed. A conventional cutting blade is preferably positioned between the sealing bar portions, being positioned for simultaneous sealing and severing operation with a single stroke of horizontal actuator


232


. Referring to

FIG. 67

, seal bar


230


″ is identical to seal bar


230


′ except that the lower seal bar portion


237


comprises a substantial mirror image of the upper seal bar portion


233


. Horizontal seal bar


230


″ is used to form the flexible package


130


shown in

FIG. 14

, with the lower seal bar portion


237


forming side seal


20


′ (shown at the left hand side of FIG.


14


).




Other seal bar portions may be used to provide flexible package side seals having configurations different from those of

FIGS. 1 and 14

. For example, with reference to

FIG. 70

, a horizontal seal bar


700


is illustrated in conjunction with a hollow conduit


702


having an opening facing the plastic web to introduce a cooling flow of air immediately adjacent seal bars


706


,


708


having expanded, spaced apart finger members


710


,


712


. The open finger-like seal bars


706


,


708


provide the tapered side seals illustrated in

FIGS. 73

,


74


. These side seals, unlike those of previous embodiments, require a substantially reduced heat input into the plastic web material with interior portions


720


of the side seals (

FIGS. 73

,


74


) being reliably formed without trapping wrinkles in the web material, as is occasionally experienced with a solid tapered web portions.




It has been observed that horizontal seal bar


706


,


708


according to principles of the present invention, having spaced branch-like finger portions, tends to iron out wrinkles that appear in the plastic web, in addition to preventing the formation of new wrinkles. Further, advantages are attained when joining multiple layers of material which are not coextensive with one another, as where different layers of material are encountered along the length of the seal bars. The arrangement of conduit


702


, even though located to one side of the seal bar arrangement and not centrally located, has been found effective to provide needed cooling to the remote bottom portions shown at the bottom of

FIG. 70

, while preventing over cooling at the upper portions of the sealed bar shown in

FIG. 10

, particularly those portions received in the cut out portion


720


.




With reference to

FIGS. 71 and 72

, peal seal bars


750


have inset portions


752


with tamper indicating indicia


754


. These seal bars are located at the uppermost position


250


in

FIGS. 40



a


,


40




b.






As pointed out above, it is important that a gap be maintained between the ends of the side seals and the stop portions


68


. Accordingly the ends


239


,


241


of horizontal seal bars


230


′,


230


″ are accurately defined and mounted for a precision fit with regard to the horizontal actuators


232


. It is important that the horizontal actuators


232


be precisely mounted with respect to the seal bands formed by vertical seal bars


254


, as can be seen with reference to the drawings for the flexible packages and the seal bands formed therein (see

FIGS. 1

,


13


and


14


, for example). The horizontal seal bars extend past the peel seal bars, and at least extend partially over the seal formed by panel seal bar


254


. So as to maintain the gap g as discussed above with respect to FIG.


13


. Referring now to

FIG. 68

, the relative positioning of the horizontal and vertical seal bars is shown.




Referring now to

FIGS. 32-44

, various methods used in the operation of apparatus


200


will be described. As mentioned above, web material is payed out from roll


204


while mated fastener track is payed out from roll


212


. End stops


68


are formed in track


210


, preferably two at a time in back-to-back mirror image relationship. The fastener track with precisely spaced stop members


68


is then passed over guide


284


to proceed in the downward feed direction of apparatus


200


(see FIG.


18


).




The web material is formed into a tube and subsequently into a flattened tube by passing over collar


800


as shown for example in FIG.


30


. Free edges of the web material are overlaid over the fastener track flanges as described above with reference to

FIG. 10

, and the overlying combination is fed between mating pairs of vertical seal bars


254


,


256


. As shown for example in

FIG. 36

, it is preferred that the vertical seal bars span several package sections of the monolithic chain of bags consisting of the unsevered combination of web and fastener track materials passing through apparatus


200


. It is important to identify which portions of the web and fastener track materials are to be combined together and properly aligned in registry with one another to form an individual flexible package, once severed from the chain of bags. Referring for example to

FIG. 31

, a position sensor


330


is located adjacent guide


284


located at the throat of the collar where free edges of the web are brought together in overlapping relationship. The position sensor is located adjacent the forming collar and most preferably is supported by the mounting collar.




It is preferred that the web sensor


330


, which controls web advancement past the seal bar station


250


and subsequent severing station, be located as close as possible to the seal bar station, without interfering with the fastener track being fed between the web free edges. According to one aspect of the present invention, web position sensor


330


is located at least within six (6) bag widths away from severing station


250


, and most preferably is located within four (4) bag widths of the sealing station (see, for example, FIG.


36


). The term “bag width” as used herein may be seen to comprise, for example, the entire width of the bag shown in

FIG. 1

or


14


, the bag width being diagrammatically illustrated in

FIG. 24

by reference lines


334


. One object of the present invention is to provide increased registration accuracy of the web and fastener tracks, and it is accordingly unsatisfactory to locate web position sensors adjacent the supply roll


204


or the accumulator rollers (not shown) located immediately adjacent thereto. In the preferred embodiment, web position sensor


330


controls operation of web drive belts


248


and may, if desired, be employed to control or provide one of several control inputs for operation of drive rollers


226


shown in FIG.


23


.




Referring to

FIG. 36

, the fastener track


210


with pre-formed stops


68


is passed between overlying free edges of web


268


and is passed between seal bars located in seal station


250


. The fastener track is precisely aligned with respect to the free edges of the overlying web portions in the manner described above with respect to FIG.


13


. The vertical seal bars are then operated to seal the fastener track to the web with actuation in the direction of arrows


340


. During machine set up, the bottom edge of the joined web and fastener tracks is fed between rollers


226


which thereafter provide automatic drive for the combined assembly.




After running a few trial steps, registration of the fastener tracks and web is checked and changes to the registration of the fastener track with respect to the web is carried out by operation of registration roller


280


which is moveable in the direction shown by the arrow in

FIG. 18. A

preferred embodiment of a registration station


344


is illustrated in FIG.


65


. The registration device of the preferred embodiment includes an idler roller engaging the mounting fastener tracks. The idler roller is mounted for movement toward and away from a neutral position so as to alter tension applied to the mated fastener tracks. Idler roller


280


is mounted on block


346


which traverses a guide channel


348


formed in mounting bar


350


. The operation of knob


352


, threaded rod


354


is rotated, causing block


346


and hence idler roller


280


to travel in the desired direction. By lowering idler roller


280


, tension in the fastener track


210


is increased and loosening of tension in the fastener track is achieved by raising the idler roller


280


. Such adjustments cause a change in relative positioning of the fastener track at sealing station


250


, with respect to those portions of the web material also located at the sealing station. Hence, with simple tension adjustments registration station


344


, registration of the fastener track and web material at the sealing station can be readily altered.




Even though spacing of the stop members


68


is otherwise provided it is important in many commercial applications to provide registration adjustment of the type mentioned herein. For example, it is commercially advantageous to provide web material which is pre-printed with individual package portions appearing in serial succession on the web material stored on supply roll


204


. With the registration adjustment station provided, relatively small adjustments in registration can be made “on the fly” during a production run, without requiring production shut down.




Referring to

FIG. 33

, after operation of the vertical seal bars, the vertical seal bars are opened in the direction indicated in FIG.


33


and horizontal actuators


232


are energized to draw horizontal seal bars


230


together. In an initial operation, during set up, the bottommost side seal of the first bag portion of the bag chain is formed. In the embodiment illustrated, for manufacture of flexible packages


10


, the side seal


22


is formed after sealing is carried out by the vertical seal bars. With reference to

FIG. 34

drive rollers


226


carry out a stepwise advance of the combined web material and fastener tracks. In a preferred embodiment, the step advance corresponds to the width of the finished flexible package (that is, the bag chain is lowered by an amount equal to one bag width). During the web advance or either immediately or shortly thereafter, contents are introduced into the flexible package as shown in FIG.


23


. The peel seal has been omitted in

FIG. 35

for drawing clarity. Package contents are preferably metered in a separate station (not shown) and fed through the upper open end


242


of mandrel


240


.




Next, with the web material and fastener tracks having been advanced, the vertical seal bars are operated in the manner indicated above with respect to FIG.


36


. Subsequently, as explained above with reference to

FIG. 21

the vertical seal bars are retracted and horizontal seal bars provide a horizontal sealing operation, defining one bag portion with respect to another. The previously formed bag portion was filled through the trailing edge of the bag, and with the subsequent horizontal sealing step, the trailing side of the bag is then sealed to form a complete enclosure for product contained therein.




In one embodiment, with the manufacture of flexible package


10


shown in

FIG. 1

, the subsequent operation of horizontal sealing bars


230


form the left-hand side seal


20


shown in

FIG. 1

, to complete sealing of the bag contents. If desired, the web material could be advanced to a new location where the right-hand side seal of the next bag is formed, this however would result in a waste of a certain amount of web and fastener track material. In

FIG. 1

, the side seals of the sides of given bag are not identical to one another. It is preferred that apparatus


200


provide horizontal types of sealing bars containing tooling for a formation of both side seals of a flexible package and that the leading side seal of a package is formed at the same time the trailing side seal of its preceding neighboring bag portion is formed. This arrangement provides a reduction in machine cycle time and also reduces registration/alignment difficulties.




Referring now to

FIG. 45

, a vertical stack of sliders


30


is accumulated in magazine


350


. In the preferred embodiment, a stack or vertical array of seven sliders is accumulated in the magazine, being collected from a conventional vibrational feed bowl (not shown). As shown in

FIG. 45

, a curved or arcuate feed slot arrangement


354


is provided downstream of magazine


350


. Preferably, contents of magazine


350


are dispensed in a continuous operation until the arcuate feed track


354


is filled in the manner shown. This brings a serial succession of sliders


30


to slider insertion device


360


which advances the sliders one at a time in a direction of arrow


362


, inserting the sliders on the free edge


364


of the bag chain


366


. With reference to

FIG. 26

, it is generally preferred that the sliders be inserted onto the fastener tracks at a point immediately downstream of guide roller


284


. Preferably, advantage is taken of the stiffening support provided by isolation bar


288


. In automated assembly operation, the isolation bar


288


“backs up” or supports the zipper track during slider insertion. The fastener track is prepared in the manner illustrated in

FIGS. 41-44

. With reference to

FIG. 31

, slider insertion takes place prior to application of the shrouded bag panels reducing interference of these flap-like continuously fed components.




Preparation of the bag chain is carried out as a preliminary measure to slider insertion. With reference to

FIGS. 41-43

, a funnel device


370


is inserted over the free edge


364


of the fastener tracks. As seen for example in

FIG. 26

, funnel device


370


includes inclined walls which catch and (with insertion over the fastener tracks in the manner indicated in

FIG. 43

) cause the fastener tracks to rock or pivot about a vertical axis so as to assume a partially open position illustrated in FIG.


43


. This opening allows the fasteners


30


to be inserted over the fastener tracks in a manner indicated in FIG.


44


. Depending upon the fastener track material chosen and the degree of compression provided by the funnel device, so-called “activation” of the fastener tracks may not be necessary.




It is generally preferred that the sliders be inserted while the bottom or leading edge of the bag portion is clamped by the horizontal sealing bars. Accordingly, provision is made for inserting sliders on the bag portion in between the vertical and horizontal sealing bars located at sealing station


250


. As indicated in

FIG. 68

, it is most preferred that the slider insertion mechanism


360


be located adjacent to the horizontal sealing bar, being spaced a fraction of the bag width above the sealing bar, so as to attain maximum rigidity from the clamping action provided. The fastener track material, however, may be soft or pliable so as to fail to provide a sufficient opening needed to receive the internal opening fin of the slider


30


. A probe


374


may be employed to provide the needed opening to receive the internal fin member of the slider. The activation opening may be positioned in-line with the slider, or more preferably, it is located to one side of the slider. The activation opening is needed to receive the internal fin member of the slider so that, when an end user first operates the slider, the internal fin member is passed between the mated fastener tracks, causing their unmating, in an opening operation.




With reference to

FIGS. 46-59

operation of the stop forming station


220


will be described. As shown in

FIG. 30

, a fastener track


210


is passed between an anvil


380


and a guide bar


382


. An opening


384


is formed in guide bar


382


to allow an ultrasonic horn member


386


access to a defined segment of the mated fastener track. The ultrasonic sealing horn


386


has a horn face


388


which forms or displaces material of track


210


into the end stops


68


shown in idealized form in

FIGS. 1 and 3

, for example. As indicated in

FIGS. 53-59

, the ultrasonic sealing horn


386


is advanced in the direction of the indicated arrow and as shown in

FIGS. 54-59

, applies pressure and frictional (ultrasonically included and residual) heating to the mated fastener tracks. It is preferred that horn face


388


act to press the mated fastener track against an anvil face which is shown in

FIG. 30



b.






With reference to

FIG. 47

, the deformation of the fastener track by horn face


388


is carried out in a central portion


392


of anvil


380


, located between spaced apart full width grooves


394


which effectively clamp the fastener track, holding it fixed in position. It is generally preferred that a pair of end stops be formed with a single operation of the ultrasonic horn, and that the end stops be positioned back-to-back in mirror image relationship. A portion of the fastener track is shown in the exploded view of

FIG. 47

with the dash line indicating a cut line which will eventually sever one bag portion from another. The width of the combined end stops


68


indicated by dimension arrows in

FIG. 47

is larger than the gap


392


and accordingly the horn face acts in concert with the preferred flat, featureless portion of anvil


380


and the reduced width groove portions


394




a


adjacent thereto. Unlike prior art arrangements forming end stops for sliders, the horn face and anvil of the present invention cooperate to produce a controlled flow of fastener track material, shifting the fastener track material to assume a precisely defined shape rather than to perform a simple flattening operation.




The ultrasonic horn face


388


is shown in the elevational view of FIG.


50


and cross-sectional view


51


. Included in horn face


388


are a series of chisel-shaped outward projections


402


, an outwardly extending wall portion


404


and recesses


406


located on either side of a lower flat surface portion


408


. A prior art ultrasonic sealing horn


410


is shown in FIG.


52


.





FIG. 55

shows an end stop


68


with line


54


-


58


indicating the line of severing, which separates one bag portion from another.

FIGS. 56 and 57

are cross-sectional views showing the profile of the desired end stop shape.

FIG. 59

shows the cross section

FIG. 56

laid against a cross-section of the fastener track in its undeformed state.





FIGS. 53

,


54


and


59


show the horn being applied to the fastener track


210


, with

FIG. 35



f


showing the final stage of operation.




The dimensions of the ultrasonic horn in

FIGS. 50-52

is as follows:

















FIGS. No.




DIMENSION




VALUE (Inch)

























31




A




0.50






″




B




0.11






″




C




0.25






″




D




0.238






″




E




0.40






″




F




0.886






″




G




0.138






″




H




0.10






″




I




0.088






″




J




0.092






″




K




0.069






″




L




0.076






32




M




0.048






″




N




0.065






″




O




0.10






33




P




1.50






″




Q




0.062






″




R




0.118






″




S




0.51






″




T




0.070






″




U




0.640














As can be seen from the comparison of the above, the ultrasonic horn according to principles of the present invention has a substantially smaller active surface area. Ultrasonic horns employed in the present invention produce substantially smaller end stops having smaller surface area and mass than prior end stops. The active surface area of the ultrasonic horn used to carry out the present invention has been found to dissipate or shed residual heat at an increased rate. As a result, deformation energy applied to the fastener track could produce a subsequent pair of back-to-back end stops as a total energy of an ultrasonic form, with the residual thermal energy being substantially reduced. This has been found to offer advantages in a high speed production environment. For example, end stops formed according to the present invention have a substantially improved, better defined shape and formation of end stops and a high speed production environment has been found to have greater reproducibility precision in the end stop manufacturing tolerances. With the present invention, end stops can be precisely formed with the flow of fastener track material being reshaped in a controlled manner.




The drawings and the foregoing descriptions are not intended to represent the only forms of the invention in regard to the details of its construction and manner of operation. Changes in form and in the proportion of parts, as well as the substitution of equivalents, are contemplated as circumstances may suggest or render expedient; and although specific terms have been employed, they are intended in a generic and descriptive sense only and not for the purposes of limitation, the scope of the invention being delineated by the following claims.



Claims
  • 1. A method of making a flexible package for food products, comprising the steps of:providing a supply of web material defining a serial succession of wall portions; paying out the first portion of the web material; providing a supply of mated fastener tracks; paying out the first portion of the mated fastener tracks; crushing a serial succession of spaced apart portions of said mated fastener tracks to form a serial succession of spaced apart back-to-back slider stop portions which are spaced apart by the same preselected package width in the payout direction; providing a vertical forming collar having a throat; drawing the web material over the vertical forming collar in a vertical machine direction to fold the web material to form a serial succession of package portions, each package portion having the same preselected package width and overlapping wall portions with overlying free ends and shroud portions at the free ends, and intermediate portions spaced from the shroud portions; sensing the position of each of said package portions with a sensor located at or adjacent the throat of said vertical forming collar, said sensor sending sensor signals indicative of the positions of said package portions; aligning the mated fastener tracks in-line with the intermediate portions; aligning the package portions of said web material in the payout direction with the back-to-back slider stop portions of said mated fastener tracks in response to said sensor signal to register said first portion of the mated fastener tracks with said first portion of web material; providing a supply of sliders; dispensing the sliders one at a time; inserting the sliders on the mated fastener tracks between the back-to-back slider stop portions; joining at least a part of the mated fastener tracks to the intermediate portions of the web material; forming a peel seal adjacent the intermediate portions; forming a transverse, leading, side seal in said overlapping portions to cooperate with said peel seal and said overlapping portions to form a pouch with an upper side seal opening; advancing the joinder of the web material and the mated fastener tracks in the vertical machine direction; filling the pouch with product through the upper side seal opening; forming a transverse trailing side seal between said overlapping portions to seal the contents of the pouch; and severing the pouch from the web material and mated fastener tracks to form a separate flexible package.
  • 2. The method of claim 1 further comprising the step of sealing the shroud portions together so as to enclose said mated fastener tracks in at least the portion of said slider.
  • 3. The method of claim 2, further comprising the step of forming a weakening line in at least one of said wall portions extending from a notch in the sidewall.
  • 4. The method of claim 3 further comprising the step of forming a tear line in at least one of said wall portions along the line extending below said mated fastener tracks and intersecting said termination point.
  • 5. The method of claim 1 further comprising the step of forming a slider-receiving opening in at least one of said wall portions to receive a portion of said slider.
  • 6. The method of claim 1 wherein the step of inserting the slider is performed before the step of joining the mated fastener tracks to the intermediate portions.
  • 7. The method of claim 1 further comprising the step of providing the mated fastener tracks with depending flanges for joining to said overlapping portions.
  • 8. The method of claim 7 wherein the step of forming a peel seal comprises joining one of the flanges to one of the overlapping portions.
  • 9. The method of claim 1 wherein the step of lengthwise aligning the package portions of said web material with the back-to-back slider stop portions of said mated fastener tracks comprises lengthwise shifting of said first portion of the mated fastener tracks to register said first portion of the mated fastener tracks with said first portion of web material.
  • 10. The method of claim 1 wherein the step of drawing of the web material over the collar to fold the web material forms a dead fold comprising a bottom end of the flexible package.
  • 11. The method of claim 1 wherein the mated fastener tracks include downwardly depending flanges and the step of the joining at least a part of the mated fastener tracks to the free ends of the overlapping portions comprises the step of providing a heat shield and inserting the heat shield between the flanges while applying the seal bars to the overlying free ends to joining the overlying free ends to respective flanges.
  • 12. The method of claim 11 wherein the step of providing a heat shield includes suspending the heat shield from the collar.
  • 13. The method of claim 1 further comprising the steps of:providing a knife blade; providing a side seal bar for forming the transverse, leading side seal; mounting the knife blade to side seal bar; and applying the side seal bar and knife blade to the first pouch to simultaneously carry out the steps of severing the pouch and forming said transverse trailing side seal.
  • 14. The method of claim 1 further comprising the step of opening at least a portion of said mated fastener tracks in preparation for receiving the slider.
  • 15. The method of claim 14 wherein said mated fastener tracks have a free edge and wherein the step of opening at least a portion of said mated fastener tracks comprises compressing said mated fastener tracks at a point spaced from said mated fastener tracks free edge to rock said mated fastener tracks against one another to form an opening at the free edge of said mated fastener tracks.
  • 16. The method of claim 15 wherein said step of compressing said mated fastener tracks comprises providing a funnel and passing said funnel over the free edge of said mated fastener tracks to apply a compressive force to said mated fastener tracks.
  • 17. The method of claim 1 further comprising the steps of:providing an idler roller; mounting the idler roller for movement toward and away from a neutral position; passing the mated fastener tracks over the idler roller; and moving the idler roller so as to alter tension on the mated fastener tracks to thereby register said first portion of the mated fastener tracks with the first portion of said web material.
  • 18. The method of claim 1 further comprising the steps of:providing a trailing side seal bar for forming the transverse, trailing side seal of a leading pouch; providing a leading seal bar for forming a transverse, leading side seal of a following pouch; providing a knife blade; mounting the knife blade between the trailing side seal bar and the leading side seal bar; associating with a leading side seal bar, trailing side seal bar, and knife blade for common movement; and simultaneously contacting the pouch with the following side seal bar and the knife blade to form a working end of the web material and mated fastener tracks while contacting the working end with the leading side seal bar to form the transverse, leading, side seal.
  • 19. The method of claim 1 wherein the step of forming a leading side seal comprises the step of tapering a portion of the leading side seal adjacent the fastener tracks so as to extend in the machine direction.
  • 20. The method of claim 19 wherein the tapering step includes spacing the leading side seal from the fastener tracks.
  • 21. The method of claim 1 wherein the step of joining a least a part of the mated fastener tracks to the overlapping portions of the web material is carried out at a sealing station and the step of sensing the position of each of said package portions is carried out at a distance no greater than about four preselected package widths from said sealing station.
  • 22. The method of claim 1 wherein the step of severing the pouch from the web material and mated fastener tracks is carried out at a severing station and the step of sensing the position of each of said package portions is carried out at a distance no greater than about six preselected package widths from said severing station.
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