Patent Publication Number: US-8122687-B2

Title: Method of making flexible packages having slide closures

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention pertains to 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 
     The invention provides improved shrouded and unshrouded flexible packages. 
     One embodiment of the invention relates to a method and apparatus for forming, filling and sealing food packaging on automated in-line equipment wherein web material is reverse folded to form a folded web top and a folded web bottom with a serial succession of folded package portions downwardly depending from the web top which comprises a dead fold. After side seals are provided to form a serial succession of pouches, the dead fold at the upper end is slit to form a fill opening. After filling the upper portion is sealed to enclose product within the pouch. 
     Another embodiment of the invention relates to a reclosable flexible package including opposed front and rear panels in interlockable first and second fastener tracks. The fastener tracks include a first track with a shorter flange mated to a second track with a longer flange which includes a reverse fold. Free edges of the reverse fold of the longer flange and the free edge of the shorter flange are separated by a gap. The package includes a slider movable along the fastener tracks and an optional shroud covering the slider. Preferably, the mated fastener tracks are provided from a roll of continuous track material which is later crushed at spaced apart portions to form a series of spaced apart back-to-back slider stop portions. 
     A further embodiment of the invention relates to a reclosable flexible package in which opposed front and rear panels are joined to first and second interlockable fastener tracks. The slider is movable along the fastener tracks for closing and opening. A shroud covers the slider and at least a portion of the fastener tracks and a weakening portion in the shroud, generally coextensive with the fastener tracks, severs an upper portion of the shroud for removal. A hinged panel is provided in a lower portion of the shroud and includes a hinge line generally coextensive with and generally below the fastener tracks. With severing of the shroud portions, the hinge panel is exposed, free for downward folding about the hinge line so as to expose the fastener tracks. 
    
    
     
       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 zipper track weld 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 apparatus for constructing flexible packages according to principles of the present invention; 
         FIG. 27  is a side elevational view thereof; 
         FIG. 28  is a fragmentary view showing the plastic web; 
         FIG. 29  shows the plastic web being folded; 
         FIG. 30  is a fragmentary perspective view of the web folding operation; 
         FIGS. 31 and 32  are fragmentary perspective views of a web sealing operation; 
         FIG. 33  is a perspective view of a package filling station; 
         FIG. 34  is a perspective view of work stations performing operations on a mated zipper track; 
         FIG. 35  is a cross-sectional view of a package immediately following a flange sealing operation; 
         FIG. 36  is a cross-sectional view similar to that of  FIG. 35  but showing sealing tools for sealing the fastener track to the package sidewalls; 
         FIG. 36   a  is a fragmentary view of  FIG. 36  taken on an enlarged scale; 
         FIG. 37  is a fragmentary perspective view of a side sealing station; 
         FIG. 38  is a fragmentary perspective view of a normal folded web and mated fastener track assembly, prior to sealing operation; 
         FIG. 38   a  is a cross-sectional view similar to that of  FIG. 38 , but showing a reverse folded web; 
         FIG. 39  is an elevational view of a flexible package constructed according to principles of the present invention; 
         FIG. 40  is a fragmentary perspective view of a package severing station; 
         FIG. 41  is a fragmentary perspective view showing filling of the flexible package; 
         FIG. 42  is a cross-sectional view taken along the line  42 - 42  of  FIG. 41 ; 
         FIG. 43  is a top plan view thereof; 
         FIG. 44  is a fragmentary perspective view of a work station preparing flexible package for filling; 
         FIG. 45  is a perspective view of a station for sealing bottom portions of a pair of flexible packages; 
         FIG. 46  is a cross-sectional view taken along the line  46 - 46  of  FIG. 45 ; 
         FIG. 47  is a cross-sectional view of the package of  FIG. 39 , shown in an inverted position; 
         FIG. 48  is a fragmentary elevational view of a further embodiment of a flexible package; 
         FIG. 49  is a fragmentary elevational view of another embodiment of a shrouded flexible package; 
         FIG. 50  is a cross-sectional view taken along the line  50 - 50  of  FIG. 49 ; 
         FIG. 51  is a cross-sectional view similar to that of  FIG. 50 , shown with the schematic depiction of tooling to form the flexible package; 
         FIG. 52  is a fragmentary elevational view of a further embodiment of a shrouded flexible package; 
         FIG. 53  is a fragmentary elevational view of another embodiment of a shrouded flexible package; 
         FIG. 54  is a cross-sectional view similar to that of  FIG. 50  but showing an alternative shroud construction; 
         FIG. 55  is a fragmentary elevational view of a further embodiment of a shrouded flexible package; 
         FIG. 56  is a fragmentary view of  FIG. 55 , shown on an enlarged scale; 
         FIG. 57  shows the flexible package partially opened; 
         FIG. 58  is an elevational view of another flexible package; 
         FIG. 59  is a cross-sectional view taken along the line  59 - 59  of  FIG. 58 ; 
         FIG. 60  is cross-sectional view taken along the line  60 - 60  of  FIG. 58 ; 
         FIG. 61  is a view similar to that of  FIG. 60  with the addition of application tooling; 
         FIG. 62  is a fragmentary elevational view of another flexible package according to principles of the present invention; 
         FIG. 63  is a fragmentary elevational view of another flexible package; 
         FIG. 64  is a fragmentary elevational view of another flexible package; 
         FIGS. 65 and 66  are fragmentary elevational views of another flexible package; 
         FIG. 67  is a fragmentary perspective view of a web folding and pre-sealed station. 
         FIG. 68  is an elevational view for constructing packages according to principles of the present invention; 
         FIG. 69  is a fragmentary cross-sectional view taken along the line  69 - 69  of  FIG. 68 ; 
         FIG. 70  is a fragmentary perspective view of the final sealing operation of  FIG. 68 ; 
         FIG. 71  is a cross-sectional view taken along the line  71 - 71  of  FIG. 68 ; 
         FIG. 72  is a cross-sectional view taken along the line  72 - 72  of  FIG. 68 ; 
         FIG. 73  is a perspective view of an alternative flexible package according to principles of the present invention; 
         FIG. 74  is perspective view showing the flexible package of  FIG. 73  partially opened; and 
         FIGS. 75 and 76  are fragmentary elevational views showing alternative flexible packages according to principles of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings and initially to  FIGS. 1-8 , a 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. A fold line with panels  12 ,  14  is formed from a continuous sheet of plastic material, or with a conventional gusseted bottom construction. 
     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.  FIG. 2  shows the upper portion of a pair of mated fastener tracks. As will be seen herein, lower portions of the fastener tracks include flanges of various constructions, including flanges of unequal length, flanges of equal length joined at their lower ends, and flanges of unequal lengths where the longer flange has a reverse fold. 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. 
     These and other flexible packages according to principles of the present invention have 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 g 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  10  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&#39;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  200 , is shown. Package  200  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  200 , 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  22  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  200  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  200  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 scoring. 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  200  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  200  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  200 , as is preferred, with the other flexible packages shown herein, is formed by a dead fold  258 . However, a gusseted bottom construction can also be employed if desired. 
     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  generally 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 . 
     If desired, the enlarged tapered side seals and/or the peg holes can be omitted. Flexible package  270  includes a continuous shroud  205  similar to that described above with reference to  FIG. 19 . Shroud  205  is continuous or unbroken in that it lacks a hole or opening for slide member  30 . However, shroud  205  does include a region  207  which is transparent or free of printing indicia  209  which is applied to the remainder of the shroud material. 
       FIG. 24  is a cross-sectional view of a flexible package  280  substantially identical to flexible package  200 , 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. 
     Other package constructions contemplated by the present invention will be described after the following description of apparatus for manufacturing improved flexible packages having slide closures. With reference to  FIG. 26  and following, apparatus according to principles of the present invention, generally indicated at  300 , employs a horizontal form fill seal arrangement with the in-line application of mated fastener tracks to a reverse (i.e., upside down) folded web. Apparatus  300  brings all of the required packaging components together, for assembly, at the point of fill and final sealing. 
     Referring to  FIGS. 26 and 27 , apparatus  300  includes a web supply roll  304  providing a supply of web material  306  preferably comprising a conventional plastic packaging film. As will be seen herein, the flexible packages or bags are formed in an inverted, or upside down position. Referring to  FIG. 28 , punches  312 ,  314  are schematically indicated and form the openings on opposed bag panel portions  12 ,  14  for the slider member. Also, indicated in  FIG. 29  are diamond shape cutouts  324  formed by punches schematically indicated in  FIG. 28  at  314 . As indicated in  FIG. 26  and elsewhere, such as  FIGS. 29 and 30 , web  306  is “reverse” folded about its longitudinal center line to form a “dead fold”  320  which would otherwise form the end of the finished packages. However, according to principles of the present invention, as will be seen herein, the dead fold  320  is subsequently slit for package filling operations and is later resealed in either a fin seal or a gusseted construction to form a finished seal at the bottom of the flexible packages. The lines  326  (see  FIG. 30 ) running generally transverse of web  206  indicate severing lines which divide one bag portion from another, the bag portions preferably being serially formed from a common web. The severing also severs back-to-back mirror image stop portions which are “stomped” or “crushed” in the zipper track, at station  360  (see  FIGS. 26 and 34 ). Cutting is carried out at station  460  as shown in  FIG. 26 . After cutting, the diamond cutouts  324  are divided to become V-shape tear notches  210  shown for example in  FIG. 39 . 
     As indicated in  FIG. 25  and in preceding figures, openings  214  are preferably formed in the side panels to allow room for the slider members and to accent the slider members to consumers alerting them immediately to the presence of a slider member, even before opening the package. The slider openings are preferably formed in the web material prior to delivery for package construction (see  312 ,  314  in  FIG. 29 ). The slider openings, as with the diamond cut outs and indicia imprinted on the web material are equally spaced at predefined intervals to facilitate subsequent high speed automated production when the web material and fastener tracks are continuously aligned. The periodic spacing is referred to as a “bag width” and is visualized by lines  326  shown in  FIG. 30 . 
     Referring to  FIGS. 26 ,  29  and  30 , a supply of mated fastener track  210  (preferably comprising fastener tracks  26 ,  28 ) is supplied on roll  350 . As mentioned, the fastener tracks can take a variety of different cross-sectional shapes, all of which can be accommodated by apparatus  300 . Generally, the fastener tracks include respective mounting flanges which at least partly overlie one another, and which extend along the mated fastener tracks. As can be seen in  FIGS. 35 and 36 , the mounting flanges of the illustrated embodiment are of unequal height (with the food package viewed in an upright position) and extend different amounts from the fastener tracks. Further details concerning the construction and operation of these 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. 
     With reference to  FIG. 29 , the mated fastener track  210  is fed through a roller guides  354  to enter a work station generally indicated at  360  for forming stops  68  in the mated fastener track. An adjacent work station  364  is provided for applying slide members  30  to the fastener track. 
     Turning again to  FIG. 26  and with additional reference to  FIG. 31 , the prepared zipper track (with end stops and slider members) and the reverse folded web is brought together at fastener sealing station  400 .  FIG. 38   a  shows a cross section of the reverse folded web and fastener track prior to entering the sealing station. As shown, web  306  is folded into an inverted general V-shape to form opposed front and rear panels  402 ,  404  joined by a dead fold  320 . As shown in figures, a serial succession of folded package portions depends downwardly from dead fold  320 . Each folded package portion has the same pre-defined package with and includes overlapping first and second package side walls with an upper package portion end including overlying free ends located remote from the dead fold  320  and a lower package portion end adjacent the dead fold, and with intermediate portions between the upper and lower package portion ends. In the preferred embodiment, the upper package portion ends include shroud portions although the shroud feature can be omitted if desired. Thus, it can be seen that the package portions of the reverse folded web are oriented in an upside down manner while being processed through the package forming apparatus. The mated fastener track includes mated male and female track members  26 ,  28  as described above, for example, with reference to  FIG. 2 . Track members  26 ,  28  of this embodiment include a longer depending flange  12  and a shorter depending flange  14 , respectively. The side  14   a  of flange  14  is joined to the opposing interior surface  402   a  of panel  402 , and the lower surface portion  12   a  is joined to panel surface  402   a . The outwardly facing surface portions  12   b  and  12   c  are joined to the opposing interior surface  404   a  of panel  404 . As mentioned, the mated fastener tracks are crushed or stomped to form a serial succession of spaced apart back-to-back slider stop portions. The slider stop portions are spaced apart by the same pre-selected package width as that of the web material. The mated fastener tracks and web material are registered or aligned to one another according to the common bag width spacing. In this manner, the fastener track material can be processed ahead of time and the web material can be pre-printed and pre-punched at a convenient, preferably remote location. 
     As will be seen herein, the mated fastener track flanges are either coupled or directly sealed to the package side walls so as to form a peal seal such as that shown in  FIG. 36   a . If desired, the zipper track flanges can be sealed directly to respective side wall panels, omitting the peal seal feature. If desired, the fastener track flanges in this optional form can be of generally equal length. However, in the preferred embodiment, the first fastener track is provided with a shorter flange and is mated to a second track with a longer flange. Preferably, the step of coupling the first and second fastener track flanges to the intermediate portions of respective package side walls comprises a first step of sealing the first fastener track flange to the intermediate portion of the first package side wall and a second step of sealing a peal seal between a portion of the second fastener track flange and a portion of the first package side wall at a point between the fastener tracks and the bottom package portions. In a third step, the second fastener track flange is sealed to the second package side wall as shown for example in  FIG. 47 . 
     Referring to  FIG. 29 , the fastener track is aligned with the underside of web  306  and is tacked to the flat, unfolded web  306  by sealing members in a preliminary sealing step using tools  401 ,  403  prior to folding of the web which might otherwise misalign the zipper track and web materials. Either of the fastener track flanges can be sealed to the web material in the preliminary sealing step. When the fastener track  2040  of  FIG. 59  is employed, it is generally preferred that a pre-seal portion of the longer flange be tacked to the web material in the preliminary sealing step. 
     As indicated above, web  306  is pre-printed and pre-punched with different types of punches, prior to package assembly. Track  210  is deformed or crushed prior to station  400  at defined intervals to form mirror image back-to-back stop portions which are severed into equal half portions at slitting station  460 . It is important that the deformed zipper tracks and pre-formed web material be carefully aligned and registered one to the other according to the pre-determined bag width spacing referred to above. Preferably, web sensors are located adjacent upstream punch  312  as schematically indicated at  313  (see  FIG. 29 ). An output from sensor  313  is fed to controller  315  which may take any conventional form, but preferably comprises a programmable digital computer. Controller  315 , in turn controls operation of stop forming station  360 , providing precise “bag width” spacing of deformed stop portions along the length of track  210 . Controller  315  also controls the precise placement of sliders onto track  210 , at station  364 . 
     With reference to  FIGS. 29 ,  30  and  31 , controller  315  also controls operation of drive rollers  409  which drive the joined assembly of fastener tracks and folded web material. For example, with reference to  FIG. 31 , a fusion sealing station is located immediately downstream of pre-folding station  400  shown in  FIG. 29  (see  FIGS. 31 ,  32 ). Drive rollers  409 , located downstream of the reverse folding plow drive the folded web  306  in the downstream direction of arrow  405   a .  FIG. 31  shows an alternative track pre-sealing operation in which the mated fastener track  210  is fed between the folded panel portions of web  306  and is fusion sealed to the web panels by track fusion sealing die  420 ,  422 . Thus, when employing the alternative arrangement shown in  FIG. 31 , the flat web sealing die  401 ,  403  of  FIG. 29  are omitted. A guide member  411  is interposed between the track sections. The panels are open at the bottom, allowing free access for tooling such guide member  411 , as shown in  FIG. 31 . With reference to  FIG. 36 , for the preferred flexible package, three pairs of sealing dies are required. The middle pair of sealing dies indicated by reference numerals  410 ,  412  cooperate with the arrangement shown in  FIG. 31  to provide a permanent or fusion seal of the zipper track to the web. In the arrangement indicated in  FIG. 31 , sealing dies  410 ,  412  provide the only joinder of the zipper track to the web material. Referring to  FIG. 32 , if the flexible package is to be constructed without a shroud member, the sealing dies  710  are omitted. 
     Referring now to  FIG. 32 , an arrangement similar to that of  FIG. 31  is shown. The arrangement of  FIG. 32  is substantially identical to that of  FIG. 31 , except that the web is folded such that the rear panel  404  is slightly shorter than the front panel  402 , so as to expose the rearwardly facing mating track. This arrangement allows a user ready access to the zipper or fastener tracks. As will be seen herein, the zipper track can, alternatively, be joined to the web after the web is folded. In this arrangement, the sealing dies  710  are not needed. 
     Sealing of the prepared fastener track to the side wall panels is carried out at pre-folding station  400 , which can accommodate normal as well as reverse folded webs. With reference to  FIG. 36 , six horizontal sealing tools are arranged in three pairs. The middle pair of sealing tools or dies includes sealing die  410  adjacent panel  402  and sealing die  412  adjacent panel  404 . As will be seen herein, panel  402  preferably comprises the front panel of the flexible package while panel  404  comprises the opposed, rear side of the package. If desired, printing on the front and rear panels  402 ,  404  could be interchanged one for the other. A normally folded web is shown in  FIG. 36 , although a reverse folded web could be processed without change of tooling. Thus the pre-folding station provides flexible dual mode operation. 
     As mentioned, it is desired that flange  14  be welded or otherwise joined to panel  402  and the longer flange  12  be joined to the panel  404 . Accordingly, sealing tools  410 ,  412  are heated to a temperature sufficient to cause welding or joining. Preferably, sealing is accomplished with the application of pressure and accordingly the sealing tools are mounted for movement toward and away from one another. In order to prevent inadvertent sealing of fastener flanges  12 ,  14  by sealing tool  410 , an unheated separator tool  416  is temporarily placed between flanges  12 ,  14 . Preferably, both sealing tools  410 ,  412  are advanced toward one another, toward separator tool  416 . As mentioned above, the dead fold  406  forms the top of the shroud in the completed flexible package. If desired, the top of the shroud can be reinforced with a sealing fin, using sealing tool  710  to weld the area adjacent the dead fold  406 . 
     Flange  14  is welded to panel  402 , and the longer flange  12  is welded to the panel  404 . Accordingly, sealing tools  410  and  412  are heated to a temperature sufficient to cause joining of flanges  12 ,  14  to panels  402 ,  404  respectively. In order to prevent inadvertent sealing of fastener flanges  12 ,  14  by sealing tool  410 , an unheated or cooled separator tool  416  is temporarily placed between flanges  12 ,  14 . Preferably, both sealing tools  410 ,  412  are advanced toward one another, toward separator tool  416 . The joinder of the lower surface portion  12   a  of flange  12  and panel  402  forms a conventional peel seal whereas the joinder of flange  14  to panel  402  comprises a permanent seal, as shown in  FIG. 36 , which shows formation tooling, using either normal or reverse fold techniques. 
     With reference to  FIGS. 36 and 38 , it is desired that the end portion of interior face  12   a  be joined to panel  402  to form a peel seal. Accordingly, a pair of sealing tools  420 ,  422  are advanced toward one another to bring flange face  12   a  in contact with the opposed interior surface  402   a  of panel  402  and to form a permanent seal between end portion  12   c  and face  404   a  of panel  404 . If desired, a sealing tools  420 ,  422  can have generally flat, opposing faces as with sealing tools  410 ,  412 , for example. However, it has been found desirable to enhance the seal strength on both faces of the free end of flange  12 , in order to prevent product intrusion or “creep” during filling. In order to facilitate high production speeds and rapid filling operations, attention must be given to the impingement or impact force of the product falling in area  405 , as indicated in  FIG. 36 . Depending upon the materials employed, impingement forces in the area  405  might tend to separate the peel seal and permanent seal formed at the free end of flange  12 . In order to facilitate the use of light weight packaging films for the package panels and to otherwise enhance the sealing strength in area  405 , it has been found desirable to provide the mating faces of sealing tools  420 ,  422  with an interlocking ridge and groove patterns. As indicated in  FIG. 36 , it is preferred that the opposing faces of sealing tools  420 ,  422  have curved, rounded features so as to allow higher heat loadings without undesired cutting as would otherwise result from the use of sharp or sharply rounded tooling seal features. Although a single, simple nested curve could be employed for the seal tools  420 ,  422 , a double reentrance or generally S-shape is preferred. 
     Turning now to  FIG. 37 , the joined web and prepared fastener tracks are advanced to the station  430 . Pairs of vertical sealing bars  432  cooperate to form reduced length side seals for the flexible package. Turning now to  FIG. 35 , it can be seen that side seals  327  are of reduced height in two ways. First, the side seals  327  stop short of dead fold  320 , and second the side seals  327  also stop short of end stops  68  formed along track  210 , as indicated by gap g in  FIG. 25 , so as to provide an intervening spacing. In this manner, unwanted deformation of the end stop is avoided as the side seals are formed. Accordingly, the vertical sealing bars  432  are foreshortened with respect to the overall height of the flexible package. 
     In the preferred embodiment, sealing bars  432  have heat loadings optimized for rapid assembly. Accordingly, it has been found desirable to add vertical cooling bars  434  at a downstream position to withdraw heat from the side seals. As mentioned above, the vertical sealing bars are foreshortened with respect to the overall height of the flexible package. The vertical cooling bars could also be foreshortened in a similar manner, since their function is to withdraw excess heat lingering after fusion of the side seals is completed. Alternatively, the cooling bars can extend upward beyond the side seals, if desired. If desired, additional operations such as forming peg holes on the side panels with punches  438  can be performed while the bag chain or serial succession of folded package portions is temporarily stopped at station  430 . If desired, the punching operation or other operations on the bag panels can be carried out at station  450  located immediately downstream of station  430  (see  FIG. 26 ). 
     Referring again to  FIG. 35 , the bag portions are connected together in a serial succession in the form of a bag chain. As mentioned, a gap is provided between side seals  327  and dead fold  320  to allow the unimpeded relative travel between the bag chain and the slitting knife  440  located either at alternate work station  450  or at a point between work stations  430  and  450 . Slitting knife  440  is preferably held in a stationary position as the bag chain travels in the direction of arrow  442  to slit the dead fold, forming a fill opening. In this manner, the individual bag portions are readied for forming and filling while providing a number of manufacturing advantages, such as improved positional stability for the bag chain immediately prior to subsequent operations. Top filling and final sealing of the upper end of the flexible packages remains to be accomplished. If desired the filling and final, top sealing could be performed with the flexible packages serially connected in a bag chain. However, it is preferred that the individual, partially formed flexible packages be separated from one another at station  460 . 
     With reference to  FIG. 40 , a series of guillotine-type knives  462  are employed to sever the bag chain to separate the empty, partially formed flexible packages at the end of the bag chain. Knives  462  are aligned so as to intersect the diamond-shaped openings  324 , forming opposed V-shaped notches in side seals of adjacent flexible packages. Knives  462  are also aligned so as to divide end stop portions formed in the fastener track at station  360 . 
     Referring again to  FIG. 40 , drive rollers  461  engage the bag chain for feeding in the forward direction of arrow A 461 . Preferably, the bag chain is advanced in a stepwise manner, bringing various portions of the bag chain to appropriate work stations, as described above. Controls for managing operation of drive rollers  461  can be located anywhere along the bag chain. As mentioned, sensors are preferably located immediately upstream of the punch station which contains punches  312 ,  314 . Controller  315  (see  FIG. 29 ) is preferably employed to control operation of drive rollers  461  (see  FIG. 40 ). 
     It is generally preferred that V-shaped notches be formed in both side seals of the flexible packages. It is generally preferred that the portions of the bag chain be supported prior to the severing operation so as to maintain positional control of the severed flexible packages. Any of a number of conventional supports, such as vacuum operated suction cups can be employed for the purpose. 
     Referring to  FIG. 33 , upper suction cups  468  are diagrammatically illustrated as spanning a pair of partially formed flexible packages. Preferably, a pair of suction cups  468  are employed, on opposite sides the flexible packages so that, by withdrawing the suction cups away from one another, the upper ends of the flexible packages are opened. At station  480  the interior portions of the flexible packages are inflated in a gas flushing operation. Any suitable gas mixture could be employed, although it is generally preferred that an inert gas for gettering or otherwise displacing oxygen is employed. The separated, but incompletely formed, flexible packages are advanced to filling station  500 . 
     Turning now to  FIGS. 33 ,  41  and  42 , duck bill filling apparatus  506  preferably has an articulated clam shell configuration. The bottom ends  508  of the clam shell members are initially brought together so as to facilitate penetration into the interior of the flexible package. The clam shell members are then opened in the manner indicated in  FIG. 42  to allow product  520  to drop into the flexible package.  FIG. 43  shows the relatively large filling opening made available. 
     With filling of the flexible package being completed, a final sealing operation is performed. With reference to FIGS.  26  and  44 - 46 , the flexible packages are advanced to sealing station  600  containing conventional linear stretching apparatus  602 . The flexible packages are then advanced to sealing station  700  where the free edges at the bottoms of the flexible packages are sealed. With reference to  FIGS. 45 and 46 , a pair of sealing bars  750  are employed. As indicated in  FIGS. 46 and 47 , a fin seal  752  is formed at the bottom of the bag, thus completing formation of the flexible package. If desired, a gusseted construction could be employed at the bottom of the bag. 
     In addition to advantages described above with reference to the apparatus and method of filling flexible packages, it will be appreciated that the reclosable fastener tracks remain engaged or mated in the closed position throughout the forming, filling and sealing of flexible packages constructed according to principles of the present invention. This reduces the number of unit operations which would otherwise be required to open and reclose the fastener tracks. Further, the working surfaces of the fastener tracks are not exposed to product, dust and particles, which could interfere with reliable mating of the fastener tracks, and the ability of the slider member to move freely. As indicated, for example, in  FIG. 35  the longer flange is preferably associated with the male fastener track  26 . As seen above, the longer flange, at its bottom end, forms a peel seal with a package panel. The shorter flange, associated with the female fastener track  28  is permanently joined to the package panel at an early stage of operation. 
     Referring now to  FIGS. 48  and following and initially to  FIG. 55 , an improved package according to principles of the present invention, is shown. Package  1200  includes the features of flexible package  10 , described above and in addition includes a shroud portion  1204  extending above line of weakness  1208  formed in panels  1012 ,  1014 . Line of weakness  1208  can be formed using available conventional techniques, and is preferably formed using laser cutting/scoring techniques. Preferably, line of weakness  1208  extends across the width of flexible package  1200 , from one side edge to the other. As shown line of weakness  1208  extends between side seals  1020 ,  1022  (see  FIG. 49 ). 
     Preferably, shroud  1204  is made for easy tear-away removal in an intuitive manual operation not requiring special directions. Preferably, a tear-start feature  1210  is formed in edge  1018 , and is located slightly above stop  1068 . The tear-start feature  1210  preferably takes the form of a slit ( FIG. 48 ), but could also comprise an extended line or other weakening feature, if desired ( FIG. 49 ). In the preferred embodiment, as illustrated, the tear-start feature  1210  comprises a linear slit extending toward an opening  1214  which surrounds slider  1030 . In the preferred embodiment, the slit line comprising tear-start feature  1210  spaced from opening  1214  and is terminated within a fin seal  1220 . If desired, the slit line could extend across the fin seal in a desired, could be made to extend immediately adjacent to or communicating with opening  1214 . As will be described more fully herein, opening  1214  has a pointed or acute angle end  1214   a  and the slit line comprising the tear-start feature  1210  is generally aligned with the direction of the pointed end  1214   a  of opening  1214 . These features combined to form a convenient directional assist to a consumer during a tear-open operation, ensuring that the tear will continue to a weakening line along with the shroud is severed from the remainder of the flexible package. As will be seen herein, the line of weakness is preferably formed with a laser cutting/scoring operation which ensures a smooth, continuous severing of the shroud from the flexible package. 
     Preferably, slider  1030  is located at a fully closed position along the fastener tracks and is surrounded by opening  1214  at the closed position. In order to gain access to the package contents, a user grasps the upper edge of shroud  1204  causing an initially tearing at tear-start feature  1210 . Tearing continues through the shroud material so as to enter opening  1214 , emerging at the pointed or acute angle end  1214   a  through a line of weakness  1208  which, as mentioned above, is preferably formed in a laser cutting/scoring operation. Optionally, as mentioned, a diagonal line may extend between the tear-start feature  1210  and opening  1214 . It is generally preferred that such optional line be aligned with the direction of the slit line  1210  and the pointed end  1214   a . With continued tearing across line of weakness  1208  separation of the shroud is continued the width of package  1200 , and the shroud  1204  is removed, leaving a package substantially similar to the packages described above in  FIGS. 31-44 . 
     Referring to  FIG. 55 , shroud  1204  includes an upper fin seal  1220  and a side fin seal portion  1222 . Preferably, the upper fin seal  1220  inside fin seal  1222  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  1222  is terminated at or slightly above end stop  1068 . It is most preferred that side fin seal  1222  be terminated slightly above end stop  1068  to avoid interfering with the controlled formation of the end stop which, as pointed out above, has a shape and position providing novel advantages. Tear-start feature  1210  in the preferred embodiment shown in  FIG. 55  is formed at the lower end of side fin seal  1222 . If desired, tear-start feature  1210  could be formed in a gap between end stop  1068  and a side fin seal shortened with respect to the side fin seal illustrated in  FIG. 55 . 
     Referring now to  FIG. 49 , flexible package  1240  is substantially identical to flexible package  1200 , except for the introduction of a line of weakness  1212  extending between the tear-start feature  1210  and the opening  1214 . The arrangement of  FIG. 49  is preferably employed where the material chosen for the flexible package or at least the shroud portion thereof is easily stretched rather than torn cleanly when subjected to a tearing force. Addition of the weakening line adjoining the tear-start feature and the opening helps to improve the directionality of the tearing force applied by a consumer. Preferably, the direction of tearing force is generally aligned with the direction of the pointed end  1214   a  of opening  1214  (see  FIG. 55 ). 
     Referring now to  FIG. 50 , a cross section of flexible package  1200  is shown. Preferably, shroud  1204  is formed as a continuous integral extension of panels  1012 ,  1014 , the upper free edges of which are joined together to form upper fin seal  1220 . The fastener track arrangement described above with reference to  FIG. 10   b  is used. 
     Referring to  FIG. 51 , exemplary tooling to form the package  1200  is shown. For example, a pair of upper seal bars  1250  form upper fin seal  1220  while a pair of intermediate seal bars  1252  join panels  1012 ,  1014  to fastener flanges  1072 ,  1074 . Lower seal bars  1254  form the peel seal  1036  and weld band  1078  ( FIG. 50 ). The bottom of package  1200 , as is preferred with the other flexible packages shown herein, is formed by a dead fold  1258 . A gusseted construction could also be employed. 
     Referring now to  FIG. 52 , a flexible package  1260  is substantially identical to flexible package  1200  of  FIG. 48 , except that the teardrop-shaped opening  1214  is modified to have a generally V-shaped end opposite the pointed end  1214   a . To ensure that tearing enters into hole  1214  as desired, it is generally preferred that weakening line  1212  bridge the distance between tear-start feature  1210  and the adjacent end of hold  1214 . 
       FIG. 53  shows a flexible package  1270  similar to that of flexible package  1200 , except that a large or tapered side seals are provided at each side of the package. Peg holes  1132 ,  1140  are formed in the tapered side seal portions and if desired an optional central peg hole can be formed in upper fin seal portion  1220 . 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  1208 . 
       FIG. 54  is a cross-sectional view of an optional flexible package  1280  substantially identical to flexible package  1200 , described above, except that a shroud member  1282  is separately formed from panels  1012 ,  1014  and is joined to the upper ends of the panels by conventional welding or other joining techniques. Most preferably, shroud  1282  is joined to the upper ends of panels  1012 ,  1014  at the point of sealing with flanges  1072 ,  1074 . The weakening line for removal of the shroud of  1282  can be formed either above or below the point of sealing with the remainder of the flexible package. 
       FIG. 56  shows an enlarged portion of flexible package  1200 , to more clearly illustrate the features of opening  1214  in cooperation of the opening or hole  1214  with the other features of the flexible package. As mentioned above, opening  1214  has a pointed end  1214   a  arranged so as to extend generally toward a central portion of the package. As shown, end  1214   a  forms an acute angle of approximately 45°. If desired, the acute angle can be extended up to 70°. The acute angle feature of end  1214   a  has been found helpful in contributing to the directionality of applied tearing force. If desired, the pointed end  1214   a  can form a sharp corner, but it is generally preferred that a rounded corner be employed, as illustrated. It has been found important for certain types of flexible package materials at the end  1214   a  be kept free of minute notches or tears. For reasons of economy, it is generally preferred that opening  1214  be used by a die cutting operation and a rounded corner  1214   a  has been found to wear in such a manner over its production life so as to avoid tearing or minute notching which could result in misdirection of the tear force applied by a consumer attempting to gain access to the interior of the flexible package. 
       FIG. 57  shows flexible package  1230  with the shroud member partially torn away. Tearing of the shroud continues along line  1208  (see  FIG. 56 ). 
     Referring to  FIG. 56 , as indicated in the figures, it is generally preferred that the opening  1214  has a lower portion extending below line of weakness  1208 , so as to further ensure that the tearing force will be applied to weakening line  1208 . If desired, opening  1214  can be lowered to bring the center of pointed end  1214   a  to intersect line of weakness  1208 . 
     As shown in  FIG. 56 , the right half of opening  1214  generally comprises a semicircle. The present invention also contemplates an arrangement where the left half of the opening also comprises a semicircle. If necessary, the size of the resulting circular opening is increased to provide a space around slider  1030  to avoid interference with the slide during opening. 
     A number of different flexible package designs have been described above, along with apparatus for constructing any of these package designs, as well as packages having various permutations and combinations of the features described above. Further, as will be seen herein, the apparatus for constructing bags and other flexible packages of various types and designs is able to fabricate a still wider variety of flexible packages having permutations and combinations of further flexible bag features to be described below. For example, apparatus and methods according to principles of the present invention have been described for use with flexible packages having slider fastener or zipper tracks. As has been seen, the flexible packages may be formed with or without shrouds covering the zipper tracks. The apparatus and methods herein are suitable for use with shrouds severable at a point below the zipper tracks from the remainder of the flexible package. As will be seen below, shrouds separable from a point above the zipper tracks may also be formed according to apparatus and methods according to principles of the present invention. Flexible packages having stress relieving features for the slide fasteners have been described above. For example, shrouds defining holes of various shapes including tear drop and rectangular and modified rectangular shape have been described. As will be seen below, shrouds can be provided according to methods and apparatus of the present invention which lack holes for relieving stress caused by bulky slide closure members. Also, shrouds lacking stress relieving holes and having printed matter or other package decoration will be described below, in which a clear window is presented to allow ready visual inspection of a slider member. Tear starting features for shroud removal have been described above. Further configurations of shroud removal tear starting weakening lines will be described below, including so-called “two-dimensional” weakening lines terminating at a point above the zipper tracks to facilitate removal of a shroud at a point located above the zipper tracks. New flexible package features especially suitable for use with shrouds removed at a point above the zipper tracks will be described below, and these features can be readily provided in apparatus and methods according to principles of the present invention. Included is a hinged flap readily configurable by a user to expose the sides of the zipper tracks. Further, methods and apparatus according to principles of the present invention have been described with reference to various flexible packages employing zipper tracks having two relatively simple flat panel flanges as shown for example in  FIG. 9 . With minimal modification the apparatus and methods according to principles of the present invention can be employed with other types of zipper fastener tracks, including those in which one of the zipper track flanges has a reverse fold. Further, a variety of flexible packages constructed according to apparatus and methods of the present invention have been described as including a sanitary peel seal located below the zipper tracks. While peel seals of this type allow a greater range of package designs, it will be readily appreciated that methods and apparatus according to the present invention can be readily employed with flexible packages which lack peel seals. 
     With reference to  FIGS. 58-66  additional features of flexible packages according to principles of the present invention, and related application tooling will be described. Referring to  FIGS. 58-61  a flexible package utilizing an optional fastener track (shown in  FIG. 59 ) provides a number of improvements relating to both package integrity and application tooling for assembly of the package. Referring to  FIG. 58 , package  2000  includes side seals  2002 ,  2004  joining front and rear panels  2008 ,  2006 . The panels are further joined by a bottom seal  2010  and a top seal  2012 . Package  2000  includes a shroud  2016  defining a tear drop hole  2018  exposing a slider  2020  which rides along mated fastener tracks. Ends of the mated fastener tracks are crushed in the manner to form end stops, as described above with regard to other embodiments herein. The end stops are identified by reference numeral  2024 . A tear notch  2026  is formed in top seal  2012  immediately above end stop  2024 . Tearing initiated at notch  2026  migrates to tear drop hole  2018  and continues along a film laser score  2030 , in the manner described above. Package  2000  can be constructed using virtually any of the construction techniques known today including bottom fill techniques or top fill either between or beside fastener tracks used for reclosing an opened package. 
     Referring now to  FIG. 59 , a zipper track assembly is generally indicated at  2040  and includes mated fastener tracks  2042 ,  2044 . Double wall flanges  2046 ,  2048  depend from fastener tracks  2042 ,  2044 . Preferably, both layers of the double wall construction comprise sealant material. The longer flange  2046  contains a reverse fold forming a rupturable bottom portion  2050 . The longer flange  2046  continues upwardly from bottom portion  2050  to form an opposed wall portion  2054  in line with shorter flange  2048  and opposing the major portion of flange  2046 . The lower end of short flange  2048  and the upper end of opposed wall portion  2054  contain adjacent spaced apart free ends  2056 ,  2058 , respectively. Bottom portion  2050 , as mentioned, is preferably formed with a dead fold construction with the fold preferably being maintained by a tack seal  2062 . Bottom portion  2050  includes a weakened area  2064  which is preferably weakened by thinning, with material being displaced into a pair of ridges  2068 . It is generally preferred that the bottom portion  2050  be sufficiently weakened so as to be readily opened by a consumer accessing the package interior after removing the optional shroud and operating the slider member so as to unmate the fastener tracks. If desired, the reverse fold weakened area can be replaced by a true peel seal of conventional design. 
     Referring now to  FIG. 60 , the zipper track assembly is shown mounted to the front and rear panels. Application tooling or die members  2070 ,  2072  form fusion seals  2074 ,  2076  and  2078 , securing the zipper track assembly to the package panels. Fusion seal  2078  joins a pre-seal portion of the longer flange to panel  2006 . Referring to  FIG. 61 , application tooling for the package forming apparatus is shown. The application tooling for package  2000  replaces the tooling shown in  FIG. 31 , which is adapted for a different zipper or fastener track assembly. 
     The zipper track assembly  2040  shown in  FIG. 59  can be readily adapted for any of the package constructions described herein, and such is contemplated by the present invention. Further, the package  2000  can be modified according to any of the package features described herein. For example, although a monolithic shroud is shown, a two-piece separately formed shroud, such as that described above could be employed, or the shroud could be omitted altogether. Although a tear drop shaped hole is shown, holes formed in the shroud can have virtually any configuration. Further, package  2000  can include a solid shroud lacking a hole for the slide member, and if desired, the solid or continuous shroud can have printing except for a transparent area exposing the slider member. Optionally, although a tear notch in the form of a short slit is shown, a S-shaped other non-linear or curved shaped slit can be employed. As a further alternative, the package  2000  can be filled beside the fastener track, before seals  2012 ,  2074  and  2076  are formed. 
     Referring now to  FIG. 62 , a flexible package  260  similar to that described above is formed with optional shroud removal features. Included is tear notch  3000  and a laser score line  3002  positioned above end stop  68 , and at or above slider member  30 . If desired, an optional bridging tear line  3004  can be employed. In  FIG. 63 , a V-shaped notch  3008  is formed in the side seal portion of the shroud, and again is located immediately above stop  68 . 
     Referring now to  FIG. 64 , a package  200  includes the laser score line  3002  located above the mated fastener tracks,  26 ,  28 . A two-dimensional tear slit  3012  extends from an edge of the package to the laser score line  3002 . In the preferred embodiment, the slit line  3012  has a generally S-shaped configuration but could have virtually any non-linear shape, smoothly curved or not. 
     Referring now to  FIGS. 65 and 66 , a flexible package  260  includes a laser score line  3002 , tear notch  3000  and optional tear notch extension  3004 . Upon opening package  260 , tearing is initiated at notch  3000  and continues to laser score line  3002 , traveling across the entire top of the package, allowing the shroud to be removed. This leaves panel portions covering opposed sides of the mated zipper tracks, the covering portions having an upper limit defined by laser score line  3002 . In order to facilitate an easier access to slider member  30  and to improve operation of the slider member as well as cleanliness upon package reuse, a hinged panel feature is provided. Included are vertical slit members  3020 ,  3022  which extend from laser score line  3002 , across the fastener tracks to a point below slider member  30 . A hinge line  3026  bridges the bottom ends of vertical slits  3020 ,  3022 . Preferably, hinge line  3026  is formed as a crease line forming a hinge for the resulting flap  3028  bounded by slit lines  3020 ,  3022  and hinge line  3026 . As shown in  FIG. 66 , the flap designated by reference numeral  3028 , is folded in a downward direction, exposing the fastener tracks  26 ,  28 , it being understood that a flap  3028  is formed on both front and rear panels of the package. A flap could be formed only in one of the package panels if improved access to only one side of the mated fastener tracks is needed. If desired, the flap could be printed with indicia instructing a user to fold the panel after removal of said shroud. 
     As shown in  FIG. 64  an optional slit  3013  can be provided above slider member  30  to relieve bulging stress caused by slider member  30 , disposed within the continuous shroud  204 . In certain applications, it is preferred that a peel seal or other barrier be provided in the package, below the fastener tracks in order to protect the package contents from the effects of breaching the package by slit line  3013 . If desired, the slit line  3013  can have a two-dimensional, i.e., non-linear shape. It is generally preferred, that the slit  3013  be spaced a sufficient distance from slit line  3012  and laser score line  3002  so as to prevent interference with operation of the shroud removal, as described above. However, it may be desirable in certain applications that the tear start feature formed at the edge of the package give rise to a tearing which communicates with slit  3013 , and traveling around slider member  30  so as to intersect laser score line  3002 . 
     Turning now to  FIG. 67 , a fastener sealing station  4000  provides many of the features described above with regard to the fastener sealing station  400  shown in  FIG. 29 . In the fastener sealing station  4000 , the fastener track enters the fastener sealing station from below, in preparation for attachment to the underside surface of the web material. It is advantageous in many instances, if the fastener track and its related preparation equipment can be disposed above the path of the web material, as shown in  FIG. 67 . In order to expose the underside surface of the web material a series of rollers  4002  turn up one edge of the web material, that edge corresponding to the upper end of the finished package, where the fastener track is applied. In the preferred embodiment, rollers  4002  turn up or fold one edge of the web material at an angle of approximately 90° with respect to the major web surface. If desired, the edge of web material can be upturned different angular amounts greater or less than 90°. 
     The fastener track material is prepared as described above with reference to  FIG. 29 . Included in the fastener track preparation our drive rollers  354 , an ultrasonic stop-forming station  360  and a slider insertion station  364 . The prepared and slider-loaded fastener track material is trained by rollers  4006  and guide  4008  into alignment with the web material, parallel to the upturned free edge  4010  of the web material. It is generally preferred that the upturned free edge  4010  be maintained generally flat, although this may not be necessary in all cases. As an optional step, the fastener track material could be tack sealed to the upturned edge of the web material to preserve the relative alignment between the fastener track and web material as they travel downstream toward the reverse folding station  4014 . 
     Although the arrangement of  FIG. 67  has been described with respect to a reverse folding operation (i.e., with the dead fold on top) it should be understood that the upturned edge arrangement for fastener sealing could be used with virtually any packaging arrangement, including formal folding operations, such as shown in  FIG. 68 , where the dead fold is located at the bottom of the folded web. Further, edge folding operations can be carried out before or after the principle web folding operation. 
     Turning now to  FIGS. 68-72 , a pre-sealing station  5000  is shown in conjunction with a horizontal form fill seal machine with bottom fill. The fastener track  210 , stop forming station  360  and slider insertion station  364  are as described above. Film  306  is unwound from supply roll  304  and passes through hole punch stations  312 ,  314  entering the zipper pre-sealing station  5000 . The prepared fastener track is sealed to film  306  by sealing dies  401 ,  403 , prior to plow folding. Preferably, the pre-sealing at station  5000  takes place while the film  360  is in a planar or flat configuration. The joined assembly of film and fastener track are then pulled over plow forming  5002  with a resulting dead fold  5004  located at the bottom of the folded web material. The pre-sealing at station  5000  either partially or fully seals the zipper to one of the two panels  5030 ,  5032  before the folding takes place.  FIG. 69  shows the zipper pre-sealing operation utilizing the zipper tracks described above in  FIG. 59 . A separator  5006  is provided and sealing die  401  is maintained in an unheated condition to assure that pre-seal  5010  occurs only on the long flange  2046  of zipper tracks  2040 . 
     After folding, the zipper tracks go through a multistep sealing operation utilizing hot, short-flange sealing dies  5008  (see  FIGS. 68 ,  70 ). In this operation, the second, shorter zipper flange  2048  is welded to the other panel. The sealing operation can also be used with additional sealing dies, to make additional seals on the flanges for tamper evidence, for example. This arrangement allows the horizontal form fill seal machine to pull the zipper tracks through all of the operations, since the zipper tracks are carried along with the web material as the web material is pulled through the machine. Mounting of the zipper tracks is more accurate as is the relative location of the fastener end stop formations and sliders which are registered to the graphics pre-printed on the web material. 
     A separator  5012  suspended from a mount  5013  is preferably employed in the final sealing station. In the preferred embodiment illustrated, the package has a shroud portion  5050 , partially defined by the dead fold  5004  at the bottom of the folded web. The joined web material and zipper tracks are advanced to the next station, shown in  FIG. 72  where hot long-flange seal bar  5040 , backed up by unheated long-flange seal bar  5042  mounts the folded portion of the longer flange  2054 . Optional hot seal bars  5044 ,  5046  at the dead fold of the web material are employed to make a header seal. It will be appreciated that the same arrangement can be employed with a reverse folding operation in which header seals  5044 ,  5046  join free ends of the folded web material in an optional arrangement. Although a bottom fill operation has been illustrated, it will be appreciated that the arrangements of  FIGS. 68-72  can be readily employed with conventional beside-the-fastener track filling operations. 
     Referring now to  FIGS. 73 and 74 , a flexible package  6000  includes an upper shroud portion  6002 , a mating fastener track assembly  6004  and an internal cavity portion  6006 . A slide fastener  6008  is mounted on the fastener track assembly in a conventional manner. 
     Flexible package  6000  includes opposed lateral seal margins  6012 ,  6014 . The flexible package has a bottom edge  6016  which may include either a margin seal or a conventional dead fold arrangement. Similarly, the upper edge of shroud portion  6002  may be formed either with a margin seal or a conventional dead fold arrangement. Shroud portion  6002  covers the mated fastener track arrangement and slide and is joined to internal cavity portion  6006  along a joining line  6020  which preferably comprises a score line and most preferably a laser-formed score line. In the preceding figures, various arrangements have been proposed for an initial tearing operation which separates the shroud portion from the remainder of the flexible package. Referring to  FIG. 64 , for example, a tear slit  3012  extends from an edge of the package to a laser score line  3002  located generally above the mated fastener tracks. In  FIGS. 73 and 74 , flexible package  6000  includes a laser score line  6020  located generally below and generally coextensive with the mated fastener tracks  6004 . Consequently, the shroud portion, when torn along the laser score line  6020  has bottom free edges  6024  formed in both front and back overlying layers comprising the shroud portion. 
     In contrast to the initial tearing arrangements described above, flexible package  6000  has a tear slit  6030  which is spaced from the lateral edge of the flexible package and which extends across the mated fastener tracks, laser score line and the full height of the slider, as can be seen in  FIG. 73 . The left marginal edge of flexible package  6000  includes a weakening member  6036  which most preferably comprises a notch formed in the left edge of the flexible package. Weakening member  6036  could also comprise a slit, if desired. As shown in  FIG. 73 , an upper end  6032  of tear slit  6030  is curved towards the left marginal edge of the flexible package and is located adjacent weakening member  6036 . Most preferably, the upper end  6032  extends slightly above the weakening member  6036  to assure that tearing initiated at the weakening member  6036  migrates toward tear slit  6030  and, regardless of the vertical component of the direction of migration (i.e., up or down) the tear line is assured of intersecting the upper portion of tear slit  6030 . Tearing then continues along slit line  6030  until the point of intersection of the slit line  6030  with the laser score line  6020 , with continued tearing extending along the laser score line in a predetermined, controlled manner. If desired, the lower end  6034  of slit line  6030  intersects score line  6020  but most preferably extends below the laser score line  6020  in the manner indicated in  FIGS. 73 and 74 . The tear line arrangement illustrated herein overcome several difficulties encountered in prior art packaging. For example, it was found that consistency of the direction of tear depends upon the gripping pattern of the consumer. Also, the comparatively bulky slider  6008  contained within the layers forming the shroud portion caused a secondary stress on the shroud portion such that an internal notch and tear was initiated in a direction in a region generally above the mated fastener tracks before the tearing tension created by the consumer reached the laser score line. With the opening arrangement according to principles of the present invention, these problems are avoided and the direction of tension of separation for removal of the shroud portion is now controlled throughout the tearing operation regardless of the gripping and pulling pattern of the consumer and the tolerances of cooperating machinery used to form the flexible package.  FIG. 74  shows the initial tearing operation. Tearing begins at the left margin of the flexible package at the line of weakness and continues to the right along a tear line propagated by the consumer until the tear slit is encountered adjacent upper end  6032 . Tearing then continues at a downward and inward direction until the laser score line  6020  is encountered. Thereafter, tearing extends along the laser score line in a desired manner. 
     Referring now to  FIG. 75 , a flexible package  6050  is substantially identical to flexible package  6000 , except for the configuration of the tear slit  6052  which includes an upper end  6054  comprising an opening or aperture connected to a line portion  6056  having a lower end  6058  communicating with laser score line  6020 . If desired, the lower end  6058  aligned portion  6056  could extend below the laser score line  6020  or, could terminate slightly above the laser score line, if desired. Cut line portion  6056  is most preferably formed as a straight line but could also include one or more curved line portions extending generally downwardly and inwardly (to the right in  FIG. 75 ) toward the center of the internal cavity portion  6006 . 
     Referring now to  FIG. 76 , flexible package  6070  is generally identical to flexible packages  6000  and  6050 , described above except for a tear slit  6072  having an upper curved portion  6074  and a lower curved portion  6076 . As indicated in  FIG. 76 , the upper curved portion  6074  extends slightly above the notch or weakening member  6036 . Tear slit  6072  extends across the full height of slider  6008  and crosses both the mated fastener tracks  6004  and the laser score line  6020  terminating at a point below the laser score line as illustrated. Tear slit  6072  may have an intermediate straight line portion between ends  6074 ,  6076  or may be continuously curved, with the curve of upper ends  6074  blended into the curve of lower end  6076 . 
     In the preceding arrangements illustrated in  FIGS. 73-76 , the tear slit extends across the full height of the slider member and is positioned adjacent, i.e., close to the slider member. In this manner, the tear slits of the various arrangements relieve stress exerted on the layers of the shroud portion by the slider member. Thus, during handling and packaging, deformation of the shroud portion due to internal expansive stresses caused by the slider are eliminated. Thus, it is assured that when the consumer initiates a tearing operation, stored internal expansive stresses within the shroud portion will not be present to mislead the desired direction of tearing. Further in each of the arrangements in  FIG. 73-76 , the upper ends of the tear slits are spaced from the weakening member at the marginal edge of the flexible package. Thus, the consumer must apply an intentional tearing motion to free the initial end of the shroud portion from the remainder of the flexible package. Accidental tearing during handling and shipping is eliminated. If desired, the laser score line could be located generally above the mated fastener tracks, although it is most preferred that the score line extend below the mated fastener tracks as illustrated in  FIGS. 73-76 . In the most preferred arrangement, the separation of the shroud portion from the remainder of the flexible package is maintained below and out of the way of the track opening through which product is dispensed by the consumer. With the tearing arrangements according to principles of the present invention, examples of which are given in  FIGS. 73-76  softer, more stretchable film materials may be used for the flexible package, with assurance that tearing will be conducted in a controlled manner despite internal stresses within the shroud portion and despite variances associated with the manipulation bearing a particular consumer-conducted tearing operation. 
     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.